retrofitted 0.18 changes

42 files changed, 879 insertions, 801 deletions

diff --git a/_test/lib/canonical.py b/_test/lib/canonical.py
index 8a00772..31c9728 100644
--- a/_test/lib/canonical.py
+++ b/_test/lib/canonical.py
@@ -348,28 +348,32 @@ ruamel.yaml.canonical_scan = canonical_scan
 
 
 def canonical_parse(stream):
-    return ruamel.yaml.parse(stream, Loader=CanonicalLoader)
+    yaml = ruamel.yaml.YAML()
+    return yaml.parse(stream, Loader=CanonicalLoader)
 
 
 ruamel.yaml.canonical_parse = canonical_parse
 
 
 def canonical_compose(stream):
-    return ruamel.yaml.compose(stream, Loader=CanonicalLoader)
+    yaml = ruamel.yaml.YAML()
+    return yaml.compose(stream, Loader=CanonicalLoader)
 
 
 ruamel.yaml.canonical_compose = canonical_compose
 
 
 def canonical_compose_all(stream):
-    return ruamel.yaml.compose_all(stream, Loader=CanonicalLoader)
+    yaml = ruamel.yaml.YAML()
+    return yaml.compose_all(stream, Loader=CanonicalLoader)
 
 
 ruamel.yaml.canonical_compose_all = canonical_compose_all
 
 
 def canonical_load(stream):
-    return ruamel.yaml.load(stream, Loader=CanonicalLoader)
+    yaml = ruamel.yaml.YAML()
+    return yaml.load(stream, Loader=CanonicalLoader)
 
 
 ruamel.yaml.canonical_load = canonical_load
diff --git a/_test/lib/test_constructor.py b/_test/lib/test_constructor.py
index 738aaec..b38bf2f 100644
--- a/_test/lib/test_constructor.py
+++ b/_test/lib/test_constructor.py
@@ -121,7 +121,7 @@ def _make_objects():
             else:
                 return False
 
-    class AnObject(object):
+    class AnObject:
         def __new__(cls, foo=None, bar=None, baz=None):
             self = object.__new__(cls)
             self.foo = foo
diff --git a/_test/lib/test_emitter.py b/_test/lib/test_emitter.py
index fbdbb79..b1991e3 100644
--- a/_test/lib/test_emitter.py
+++ b/_test/lib/test_emitter.py
@@ -1,7 +1,8 @@
 from __future__ import absolute_import
 from __future__ import print_function
 
-import ruamel.yaml as yaml
+import ruamel.yaml
+from ruamel.yaml import YAML
 
 
 def _compare_events(events1, events2):
@@ -20,8 +21,8 @@ def _compare_events(events1, events2):
 
 def test_emitter_on_data(data_filename, canonical_filename, verbose=False):
     with open(data_filename, 'rb') as fp0:
-        events = list(yaml.parse(fp0))
-    output = yaml.emit(events)
+        events = list(YAML().parse(fp0))
+    output = YAML().emit(events)
     if verbose:
         print('OUTPUT:')
         print(output)
@@ -34,9 +35,9 @@ test_emitter_on_data.unittest = ['.data', '.canonical']
 
 def test_emitter_on_canonical(canonical_filename, verbose=False):
     with open(canonical_filename, 'rb') as fp0:
-        events = list(yaml.parse(fp0))
+        events = list(YAML().parse(fp0))
     for canonical in [False, True]:
-        output = yaml.emit(events, canonical=canonical)
+        output = YAML().emit(events, canonical=canonical)
         if verbose:
             print('OUTPUT (canonical=%s):' % canonical)
             print(output)
@@ -50,7 +51,7 @@ test_emitter_on_canonical.unittest = ['.canonical']
 def test_emitter_styles(data_filename, canonical_filename, verbose=False):
     for filename in [data_filename, canonical_filename]:
         with open(filename, 'rb') as fp0:
-            events = list(yaml.parse(fp0))
+            events = list(YAML().parse(fp0))
         for flow_style in [False, True]:
             for style in ['|', '>', '"', "'", ""]:
                 styled_events = []
@@ -68,23 +69,23 @@ def test_emitter_styles(data_filename, canonical_filename, verbose=False):
                             event.anchor, event.tag, event.implicit, flow_style=flow_style
                         )
                     styled_events.append(event)
-                output = yaml.emit(styled_events)
+                output = YAML().emit(styled_events)
                 if verbose:
                     print(
                         'OUTPUT (filename=%r, flow_style=%r, style=%r)'
                         % (filename, flow_style, style)
                     )
                     print(output)
-                new_events = list(yaml.parse(output))
+                new_events = list(YAML().parse(output))
                 _compare_events(events, new_events)
 
 
 test_emitter_styles.unittest = ['.data', '.canonical']
 
 
-class EventsLoader(yaml.Loader):
+class EventsLoader(ruamel.yaml.Loader):
     def construct_event(self, node):
-        if isinstance(node, yaml.ScalarNode):
+        if isinstance(node, ruamel.yaml.ScalarNode):
             mapping = {}
         else:
             mapping = self.construct_mapping(node)
@@ -116,12 +117,12 @@ EventsLoader.add_constructor(None, EventsLoader.construct_event)
 
 def test_emitter_events(events_filename, verbose=False):
     with open(events_filename, 'rb') as fp0:
-        events = list(yaml.load(fp0, Loader=EventsLoader))
-    output = yaml.emit(events)
+        events = list(YAML().load(fp0, Loader=EventsLoader))
+    output = YAML().emit(events)
     if verbose:
         print('OUTPUT:')
         print(output)
-    new_events = list(yaml.parse(output))
+    new_events = list(YAML().parse(output))
     _compare_events(events, new_events)
 
 
diff --git a/_test/lib/test_resolver.py b/_test/lib/test_resolver.py
index 24373a7..b2b0839 100644
--- a/_test/lib/test_resolver.py
+++ b/_test/lib/test_resolver.py
@@ -1,5 +1,6 @@
 
-import ruamel.yaml as yaml
+import ruamel.yaml
+yaml = ruamel.yaml.YAML()
 import pprint
 
 
diff --git a/_test/lib/test_structure.py b/_test/lib/test_structure.py
index 470d267..8de24a3 100644
--- a/_test/lib/test_structure.py
+++ b/_test/lib/test_structure.py
@@ -84,9 +84,9 @@ def test_parser(data_filename, canonical_filename, verbose=False):
     events2 = None
     try:
         with open(data_filename, 'rb') as fp0:
-            events1 = list(ruamel.yaml.parse(fp0))
+            events1 = list(ruamel.yaml.YAML().parse(fp0))
         with open(canonical_filename, 'rb') as fp0:
-            events2 = list(ruamel.yaml.canonical_parse(fp0))
+            events2 = list(ruamel.yaml.YAML().canonical_parse(fp0))
         _compare_events(events1, events2)
     finally:
         if verbose:
@@ -104,9 +104,9 @@ def test_parser_on_canonical(canonical_filename, verbose=False):
     events2 = None
     try:
         with open(canonical_filename, 'rb') as fp0:
-            events1 = list(ruamel.yaml.parse(fp0))
+            events1 = list(ruamel.yaml.YAML().parse(fp0))
         with open(canonical_filename, 'rb') as fp0:
-            events2 = list(ruamel.yaml.canonical_parse(fp0))
+            events2 = list(ruamel.yaml.YAML().canonical_parse(fp0))
         _compare_events(events1, events2, full=True)
     finally:
         if verbose:
@@ -138,10 +138,11 @@ def test_composer(data_filename, canonical_filename, verbose=False):
     nodes1 = None
     nodes2 = None
     try:
+        yaml = ruamel.yaml.YAML()
         with open(data_filename, 'rb') as fp0:
-            nodes1 = list(ruamel.yaml.compose_all(fp0))
+            nodes1 = list(yaml.compose_all(fp0))
         with open(canonical_filename, 'rb') as fp0:
-            nodes2 = list(ruamel.yaml.canonical_compose_all(fp0))
+            nodes2 = list(yaml.canonical_compose_all(fp0))
         assert len(nodes1) == len(nodes2), (len(nodes1), len(nodes2))
         for node1, node2 in zip(nodes1, nodes2):
             _compare_nodes(node1, node2)
diff --git a/_test/lib/test_yaml_ext.py b/_test/lib/test_yaml_ext.py
index 8cba7e5..a6fa287 100644
--- a/_test/lib/test_yaml_ext.py
+++ b/_test/lib/test_yaml_ext.py
@@ -110,7 +110,7 @@ def new_safe_dump(data, stream=None, **kwds):
     return old_dump(data, stream, ruamel.yaml.CSafeDumper, **kwds)
 
 
-old_safe_dump_all = ruamel.yaml.safe_dump_all
+# old_safe_dump_all = ruamel.yaml.safe_dump_all
 
 
 def new_safe_dump_all(documents, stream=None, **kwds):
@@ -236,10 +236,12 @@ test_c_scanner.skip = ['.skip-ext']
 
 
 def _compare_parsers(py_data, c_data, verbose):
-    py_events = list(ruamel.yaml.parse(py_data, Loader=ruamel.yaml.PyLoader))
+    yaml = ruamel.yaml.YAML(typ='unsafe', pure=True)
+    py_events = list(yaml.parse(py_data, Loader=ruamel.yaml.PyLoader))
     c_events = []
     try:
-        for event in ruamel.yaml.parse(c_data, Loader=ruamel.yaml.CLoader):
+        yaml = ruamel.yaml.YAML(typ='unsafe', pure=False)
+        for event in yaml.parse(c_data, Loader=ruamel.yaml.CLoader):
             c_events.append(event)
         assert len(py_events) == len(c_events), (len(py_events), len(c_events))
         for py_event, c_event in zip(py_events, c_events):
@@ -284,12 +286,13 @@ test_c_parser.skip = ['.skip-ext']
 
 
 def _compare_emitters(data, verbose):
-    events = list(ruamel.yaml.parse(data, Loader=ruamel.yaml.PyLoader))
-    c_data = ruamel.yaml.emit(events, Dumper=ruamel.yaml.CDumper)
+    yaml = ruamel.yaml.YAML(typ='unsafe', pure=True)
+    events = list(yaml.parse(py_data, Loader=ruamel.yaml.PyLoader))
+    c_data = yaml.emit(events, Dumper=ruamel.yaml.CDumper)
     if verbose:
         print(c_data)
-    py_events = list(ruamel.yaml.parse(c_data, Loader=ruamel.yaml.PyLoader))
-    c_events = list(ruamel.yaml.parse(c_data, Loader=ruamel.yaml.CLoader))
+    py_events = list(yaml.parse(c_data, Loader=ruamel.yaml.PyLoader))
+    c_events = list(yaml.parse(c_data, Loader=ruamel.yaml.CLoader))
     try:
         assert len(events) == len(py_events), (len(events), len(py_events))
         assert len(events) == len(c_events), (len(events), len(c_events))
diff --git a/_test/roundtrip.py b/_test/roundtrip.py
index 8b87380..fa8b08a 100644
--- a/_test/roundtrip.py
+++ b/_test/roundtrip.py
@@ -8,10 +8,12 @@ import textwrap
 import io
 from pathlib import Path
 
+from typing import Any, Optional, Union
+
 unset = object()
 
 
-def dedent(data):
+def dedent(data: str) -> str:
     try:
         position_of_first_newline = data.index('\n')
         for idx in range(position_of_first_newline):
@@ -24,7 +26,9 @@ def dedent(data):
     return textwrap.dedent(data)
 
 
-def round_trip_load(inp, preserve_quotes=None, version=None):
+def round_trip_load(
+    inp: Any, preserve_quotes: Optional[bool] = None, version: Optional[Any] = None
+) -> Any:
     import ruamel.yaml  # NOQA
 
     dinp = dedent(inp)
@@ -34,7 +38,9 @@ def round_trip_load(inp, preserve_quotes=None, version=None):
     return yaml.load(dinp)
 
 
-def round_trip_load_all(inp, preserve_quotes=None, version=None):
+def round_trip_load_all(
+    inp: Any, preserve_quotes: Optional[bool] = None, version: Optional[Any] = None
+) -> Any:
     import ruamel.yaml  # NOQA
 
     dinp = dedent(inp)
@@ -45,18 +51,18 @@ def round_trip_load_all(inp, preserve_quotes=None, version=None):
 
 
 def round_trip_dump(
-    data,
-    stream=None,  # *,
-    indent=None,
-    block_seq_indent=None,
-    default_flow_style=unset,
-    top_level_colon_align=None,
-    prefix_colon=None,
-    explicit_start=None,
-    explicit_end=None,
-    version=None,
-    allow_unicode=True,
-):
+    data: Any,
+    stream: Any = None,  # *,
+    indent: Optional[int] = None,
+    block_seq_indent: Optional[int] = None,
+    default_flow_style: Any = unset,
+    top_level_colon_align: Any = None,
+    prefix_colon: Any = None,
+    explicit_start: Optional[bool] = None,
+    explicit_end: Optional[bool] = None,
+    version: Optional[Any] = None,
+    allow_unicode: bool = True,
+) -> Union[str, None]:
     import ruamel.yaml  # NOQA
 
     yaml = ruamel.yaml.YAML()
@@ -71,25 +77,25 @@ def round_trip_dump(
     yaml.allow_unicode = allow_unicode
     if stream is not None:
         yaml.dump(data, stream=stream)
-        return
+        return None
     buf = io.StringIO()
     yaml.dump(data, stream=buf)
     return buf.getvalue()
 
 
 def round_trip_dump_all(
-    data,
-    stream=None,  # *,
-    indent=None,
-    block_seq_indent=None,
-    default_flow_style=unset,
-    top_level_colon_align=None,
-    prefix_colon=None,
-    explicit_start=None,
-    explicit_end=None,
-    version=None,
-    allow_unicode=None,
-):
+    data: Any,
+    stream: Any = None,  # *,
+    indent: Optional[int] = None,
+    block_seq_indent: Optional[int] = None,
+    default_flow_style: Any = unset,
+    top_level_colon_align: Any = None,
+    prefix_colon: Any = None,
+    explicit_start: Optional[bool] = None,
+    explicit_end: Optional[bool] = None,
+    version: Optional[Any] = None,
+    allow_unicode: bool = True,
+) -> Union[str, None]:
     import ruamel.yaml  # NOQA
 
     yaml = ruamel.yaml.YAML()
@@ -104,13 +110,13 @@ def round_trip_dump_all(
     yaml.allow_unicode = allow_unicode
     if stream is not None:
         yaml.dump(data, stream=stream)
-        return
+        return None
     buf = io.StringIO()
     yaml.dump_all(data, stream=buf)
     return buf.getvalue()
 
 
-def diff(inp, outp, file_name='stdin'):
+def diff(inp: str, outp: str, file_name: str = 'stdin') -> None:
     import difflib
 
     inl = inp.splitlines(True)  # True for keepends
@@ -125,20 +131,21 @@ def diff(inp, outp, file_name='stdin'):
 
 
 def round_trip(
-    inp,
-    outp=None,
-    extra=None,
-    intermediate=None,
-    indent=None,
-    block_seq_indent=None,
-    top_level_colon_align=None,
-    prefix_colon=None,
-    preserve_quotes=None,
-    explicit_start=None,
-    explicit_end=None,
-    version=None,
-    dump_data=None,
-):
+    inp: str,
+    outp: Optional[str] = None,
+    extra: Optional[str] = None,
+    intermediate: Any = None,
+    indent: Optional[int] = None,
+    block_seq_indent: Optional[int] = None,
+    default_flow_style: Any = unset,
+    top_level_colon_align: Any = None,
+    prefix_colon: Any = None,
+    preserve_quotes: Any = None,
+    explicit_start: Optional[bool] = None,
+    explicit_end: Optional[bool] = None,
+    version: Optional[Any] = None,
+    dump_data: Any = None,
+) -> Any:
     """
     inp:    input string to parse
     outp:   expected output (equals input if not specified)
@@ -167,6 +174,7 @@ def round_trip(
         explicit_end=explicit_end,
         version=version,
     )
+    assert isinstance(res, str)
     if res != doutp:
         diff(doutp, res, 'input string')
     print('\nroundtrip data:\n', res, sep="")
@@ -187,19 +195,19 @@ def round_trip(
 
 
 def na_round_trip(
-    inp,
-    outp=None,
-    extra=None,
-    intermediate=None,
-    indent=None,
-    top_level_colon_align=None,
-    prefix_colon=None,
-    preserve_quotes=None,
-    explicit_start=None,
-    explicit_end=None,
-    version=None,
-    dump_data=None,
-):
+    inp: str,
+    outp: Optional[str] = None,
+    extra: Optional[str] = None,
+    intermediate: Any = None,
+    indent: Optional[int] = None,
+    top_level_colon_align: Any = None,
+    prefix_colon: Any = None,
+    preserve_quotes: Any = None,
+    explicit_start: Optional[bool] = None,
+    explicit_end: Optional[bool] = None,
+    version: Optional[Any] = None,
+    dump_data: Any = None,
+) -> Any:
     """
     inp:    input string to parse
     outp:   expected output (equals input if not specified)
@@ -233,20 +241,20 @@ def na_round_trip(
     return res
 
 
-def YAML(**kw):
+def YAML(**kw: Any) -> Any:
     import ruamel.yaml  # NOQA
 
     class MyYAML(ruamel.yaml.YAML):
         """auto dedent string parameters on load"""
 
-        def load(self, stream):
+        def load(self, stream: Any) -> Any:
             if isinstance(stream, str):
                 if stream and stream[0] == '\n':
                     stream = stream[1:]
                 stream = textwrap.dedent(stream)
             return ruamel.yaml.YAML.load(self, stream)
 
-        def load_all(self, stream):
+        def load_all(self, stream: Any) -> Any:
             if isinstance(stream, str):
                 if stream and stream[0] == '\n':
                     stream = stream[1:]
@@ -254,7 +262,7 @@ def YAML(**kw):
             for d in ruamel.yaml.YAML.load_all(self, stream):
                 yield d
 
-        def dump(self, data, **kw):
+        def dump(self, data: Any, **kw: Any) -> Any:  # type: ignore
             from ruamel.yaml.compat import StringIO, BytesIO  # NOQA
 
             assert ('stream' in kw) ^ ('compare' in kw)
@@ -270,11 +278,11 @@ def YAML(**kw):
             res = st.getvalue()
             print(res)
             if unordered_lines:
-                res = sorted(res.splitlines())
-                expected = sorted(expected.splitlines())
+                res = sorted(res.splitlines())  # type: ignore
+                expected = sorted(expected.splitlines())  # type: ignore
             assert res == expected
 
-        def round_trip(self, stream, **kw):
+        def round_trip(self, stream: Any, **kw: Any) -> None:
             from ruamel.yaml.compat import StringIO, BytesIO  # NOQA
 
             assert isinstance(stream, str)
@@ -291,7 +299,7 @@ def YAML(**kw):
                 diff(outp, res, 'input string')
             assert res == outp
 
-        def round_trip_all(self, stream, **kw):
+        def round_trip_all(self, stream: Any, **kw: Any) -> None:
             from ruamel.yaml.compat import StringIO, BytesIO  # NOQA
 
             assert isinstance(stream, str)
@@ -311,7 +319,13 @@ def YAML(**kw):
     return MyYAML(**kw)
 
 
-def save_and_run(program, base_dir=None, output=None, file_name=None, optimized=False):
+def save_and_run(
+    program: str,
+    base_dir: Optional[Any] = None,
+    output: Optional[Any] = None,
+    file_name: Optional[Any] = None,
+    optimized: bool = False,
+) -> int:
     """
     safe and run a python program, thereby circumventing any restrictions on module level
     imports
@@ -322,7 +336,7 @@ def save_and_run(program, base_dir=None, output=None, file_name=None, optimized=
         base_dir = Path(str(base_dir))
     if file_name is None:
         file_name = 'safe_and_run_tmp.py'
-    file_name = base_dir / file_name
+    file_name = base_dir / file_name  # type: ignore
     file_name.write_text(dedent(program))
 
     try:
@@ -335,9 +349,9 @@ def save_and_run(program, base_dir=None, output=None, file_name=None, optimized=
         res = check_output(cmd, stderr=STDOUT, universal_newlines=True, cwd=str(base_dir))
         if output is not None:
             if '__pypy__' in sys.builtin_module_names:
-                res = res.splitlines(True)
-                res = [line for line in res if 'no version info' not in line]
-                res = ''.join(res)
+                res1 = res.splitlines(True)
+                res2 = [line for line in res1 if 'no version info' not in line]
+                res = ''.join(res2)
             print('result:  ', res, end='')
             print('expected:', output, end='')
             assert res == output
diff --git a/_test/test_a_dedent.py b/_test/test_a_dedent.py
index 447bdde..e13a54b 100644
--- a/_test/test_a_dedent.py
+++ b/_test/test_a_dedent.py
@@ -4,7 +4,7 @@ from roundtrip import dedent
 
 
 class TestDedent:
-    def test_start_newline(self):
+    def test_start_newline(self) -> None:
         # fmt: off
         x = dedent("""
         123
@@ -13,7 +13,7 @@ class TestDedent:
         # fmt: on
         assert x == '123\n  456\n'
 
-    def test_start_space_newline(self):
+    def test_start_space_newline(self) -> None:
         # special construct to prevent stripping of following whitespace
         # fmt: off
         x = dedent("   " """
@@ -22,7 +22,7 @@ class TestDedent:
         # fmt: on
         assert x == '123\n'
 
-    def test_start_no_newline(self):
+    def test_start_no_newline(self) -> None:
         # special construct to prevent stripping of following whitespac
         x = dedent("""\
         123
@@ -30,17 +30,17 @@ class TestDedent:
         """)
         assert x == '123\n  456\n'
 
-    def test_preserve_no_newline_at_end(self):
+    def test_preserve_no_newline_at_end(self) -> None:
         x = dedent("""
         123""")
         assert x == '123'
 
-    def test_preserve_no_newline_at_all(self):
+    def test_preserve_no_newline_at_all(self) -> None:
         x = dedent("""\
         123""")
         assert x == '123'
 
-    def test_multiple_dedent(self):
+    def test_multiple_dedent(self) -> None:
         x = dedent(
             dedent("""
         123
diff --git a/_test/test_add_xxx.py b/_test/test_add_xxx.py
index 8beac65..5f12ece 100644
--- a/_test/test_add_xxx.py
+++ b/_test/test_add_xxx.py
@@ -1,31 +1,32 @@
 # coding: utf-8
 
 import re
-import pytest  # NOQA
+import pytest  # type: ignore  # NOQA
 
 from roundtrip import dedent, round_trip_dump  # NOQA
+from typing import Any
 
 
 # from PyYAML docs
-class Dice(tuple):
-    def __new__(cls, a, b):
+class Dice(tuple):  # type: ignore
+    def __new__(cls, a: int, b: int) -> "Dice":
         return tuple.__new__(cls, [a, b])
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         return 'Dice(%s,%s)' % self
 
 
-def dice_constructor(loader, node):
+def dice_constructor(loader: Any, node: Any) -> Dice:
     value = loader.construct_scalar(node)
     a, b = map(int, value.split('d'))
     return Dice(a, b)
 
 
-def dice_representer(dumper, data):
+def dice_representer(dumper: Any, data: Any) -> Any:
     return dumper.represent_scalar('!dice', '{}d{}'.format(*data))
 
 
-def test_dice_constructor():
+def test_dice_constructor() -> None:
     import ruamel.yaml  # NOQA
 
     yaml = ruamel.yaml.YAML(typ='unsafe', pure=True)
@@ -34,7 +35,7 @@ def test_dice_constructor():
     assert str(data) == "{'initial hit points': Dice(8,4)}"
 
 
-def test_dice_constructor_with_loader():
+def test_dice_constructor_with_loader() -> None:
     import ruamel.yaml  # NOQA
 
     yaml = ruamel.yaml.YAML(typ='unsafe', pure=True)
@@ -43,7 +44,7 @@ def test_dice_constructor_with_loader():
     assert str(data) == "{'initial hit points': Dice(8,4)}"
 
 
-def test_dice_representer():
+def test_dice_representer() -> None:
     import ruamel.yaml  # NOQA
 
     yaml = ruamel.yaml.YAML(typ='unsafe', pure=True)
@@ -55,7 +56,7 @@ def test_dice_representer():
     assert buf.getvalue() == 'gold: !dice 10d6\n'
 
 
-def test_dice_implicit_resolver():
+def test_dice_implicit_resolver() -> None:
     import ruamel.yaml  # NOQA
 
     yaml = ruamel.yaml.YAML(typ='unsafe', pure=True)
@@ -68,26 +69,26 @@ def test_dice_implicit_resolver():
     assert yaml.load('damage: 5d10') == dict(damage=Dice(5, 10))
 
 
-class Obj1(dict):
-    def __init__(self, suffix):
+class Obj1(dict):  # type: ignore
+    def __init__(self, suffix: Any) -> None:
         self._suffix = suffix
         self._node = None
 
-    def add_node(self, n):
+    def add_node(self, n: Any) -> None:
         self._node = n
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         return 'Obj1(%s->%s)' % (self._suffix, self.items())
 
-    def dump(self):
+    def dump(self) -> str:
         return repr(self._node)
 
 
-class YAMLObj1(object):
+class YAMLObj1:
     yaml_tag = '!obj:'
 
     @classmethod
-    def from_yaml(cls, loader, suffix, node):
+    def from_yaml(cls, loader: Any, suffix: Any, node: Any) -> Any:
         import ruamel.yaml  # NOQA
 
         obj1 = Obj1(suffix)
@@ -98,11 +99,11 @@ class YAMLObj1(object):
         return obj1
 
     @classmethod
-    def to_yaml(cls, dumper, data):
+    def to_yaml(cls, dumper: Any, data: Any) -> Any:
         return dumper.represent_scalar(cls.yaml_tag + data._suffix, data.dump())
 
 
-def test_yaml_obj():
+def test_yaml_obj() -> None:
     import ruamel.yaml  # NOQA
 
     yaml = ruamel.yaml.YAML(typ='unsafe', pure=True)
@@ -115,7 +116,7 @@ def test_yaml_obj():
     assert buf.getvalue() == """!obj:x.2 "{'a': 1}"\n"""
 
 
-def test_yaml_obj_with_loader_and_dumper():
+def test_yaml_obj_with_loader_and_dumper() -> None:
     import ruamel.yaml  # NOQA
 
     yaml = ruamel.yaml.YAML(typ='unsafe', pure=True)
@@ -137,25 +138,25 @@ def test_yaml_obj_with_loader_and_dumper():
 # Issue 127 reported by Tommy Wang
 
 
-def test_issue_127():
+def test_issue_127() -> None:
     import ruamel.yaml  # NOQA
 
     class Ref(ruamel.yaml.YAMLObject):
-        yaml_constructor = ruamel.yaml.RoundTripConstructor
-        yaml_representer = ruamel.yaml.RoundTripRepresenter
+        yaml_constructor = ruamel.yaml.RoundTripConstructor  # type: ignore
+        yaml_representer = ruamel.yaml.RoundTripRepresenter  # type: ignore
         yaml_tag = '!Ref'
 
-        def __init__(self, logical_id):
+        def __init__(self, logical_id: Any) -> None:
             self.logical_id = logical_id
 
         @classmethod
-        def from_yaml(cls, loader, node):
+        def from_yaml(cls, loader: Any, node: Any) -> Any:
             return cls(loader.construct_scalar(node))
 
         @classmethod
-        def to_yaml(cls, dumper, data):
+        def to_yaml(cls, dumper: Any, data: Any) -> Any:
             if isinstance(data.logical_id, ruamel.yaml.scalarstring.ScalarString):
-                style = data.logical_id.style  # ruamel.yaml>0.15.8
+                style = data.logical_id.style  # type: ignore # ruamel.yaml>0.15.8
             else:
                 style = None
             return dumper.represent_scalar(cls.yaml_tag, data.logical_id, style=style)
diff --git a/_test/test_anchor.py b/_test/test_anchor.py
index 3c83886..da0f1ef 100644
--- a/_test/test_anchor.py
+++ b/_test/test_anchor.py
@@ -4,26 +4,26 @@
 testing of anchors and the aliases referring to them
 """
 
-import pytest
-from textwrap import dedent
+import pytest  # type: ignore  # NOQA
 import platform
 
 from roundtrip import round_trip, dedent, round_trip_load, round_trip_dump, YAML  # NOQA
+from typing import Any
 
 
-def load(s):
+def load(s: str) -> Any:
     return round_trip_load(dedent(s))
 
 
-def compare(d, s):
+def compare(d: Any, s: str) -> None:
     assert round_trip_dump(d) == dedent(s)
 
 
 class TestAnchorsAliases:
-    def test_anchor_id_renumber(self):
+    def test_anchor_id_renumber(self) -> None:
         from ruamel.yaml.serializer import Serializer
 
-        assert Serializer.ANCHOR_TEMPLATE == 'id%03d'
+        assert Serializer.ANCHOR_TEMPLATE == 'id{:03d}'
         data = load("""
         a: &id002
           b: 1
@@ -40,7 +40,7 @@ class TestAnchorsAliases:
         """,
         )
 
-    def test_template_matcher(self):
+    def test_template_matcher(self) -> None:
         """test if id matches the anchor template"""
         from ruamel.yaml.serializer import templated_id
 
@@ -53,13 +53,13 @@ class TestAnchorsAliases:
         assert not templated_id('id000')
         assert not templated_id('x000')
 
-    # def test_re_matcher(self):
+    # def test_re_matcher(self) -> None:
     #     import re
     #     assert re.compile('id(?!000)\\d{3,}').match('id001')
     #     assert not re.compile('id(?!000\\d*)\\d{3,}').match('id000')
     #     assert re.compile('id(?!000$)\\d{3,}').match('id0001')
 
-    def test_anchor_assigned(self):
+    def test_anchor_assigned(self) -> None:
         from ruamel.yaml.comments import CommentedMap
 
         data = load("""
@@ -80,7 +80,7 @@ class TestAnchorsAliases:
         assert e.yaml_anchor().value == 'etemplate'
         assert e.yaml_anchor().always_dump is False
 
-    def test_anchor_id_retained(self):
+    def test_anchor_id_retained(self) -> None:
         data = load("""
         a: &id002
           b: 1
@@ -105,10 +105,10 @@ class TestAnchorsAliases:
         """,
         )
 
-    @pytest.mark.skipif(
+    @pytest.mark.skipif(  # type: ignore
         platform.python_implementation() == 'Jython', reason='Jython throws RepresenterError'
     )
-    def test_alias_before_anchor(self):
+    def test_alias_before_anchor(self) -> None:
         from ruamel.yaml.composer import ComposerError
 
         with pytest.raises(ComposerError):
@@ -120,7 +120,7 @@ class TestAnchorsAliases:
             """)
             data = data
 
-    def test_anchor_on_sequence(self):
+    def test_anchor_on_sequence(self) -> None:
         # as reported by Bjorn Stabell
         # https://bitbucket.org/ruamel/yaml/issue/7/anchor-names-not-preserved
         from ruamel.yaml.comments import CommentedSeq
@@ -165,7 +165,7 @@ class TestAnchorsAliases:
           label: center/huge
         """)
 
-    def test_merge_00(self):
+    def test_merge_00(self) -> None:
         data = load(self.merge_yaml)
         d = data[4]
         ok = True
@@ -181,7 +181,7 @@ class TestAnchorsAliases:
                     print('key', k, d.get(k), data[o].get(k))
         assert ok
 
-    def test_merge_accessible(self):
+    def test_merge_accessible(self) -> None:
         from ruamel.yaml.comments import CommentedMap, merge_attrib
 
         data = load("""
@@ -196,11 +196,11 @@ class TestAnchorsAliases:
         assert isinstance(d, CommentedMap)
         assert hasattr(d, merge_attrib)
 
-    def test_merge_01(self):
+    def test_merge_01(self) -> None:
         data = load(self.merge_yaml)
         compare(data, self.merge_yaml)
 
-    def test_merge_nested(self):
+    def test_merge_nested(self) -> None:
         yaml = """
         a:
           <<: &content
@@ -212,7 +212,7 @@ class TestAnchorsAliases:
         """
         data = round_trip(yaml)  # NOQA
 
-    def test_merge_nested_with_sequence(self):
+    def test_merge_nested_with_sequence(self) -> None:
         yaml = """
         a:
           <<: &content
@@ -225,7 +225,7 @@ class TestAnchorsAliases:
         """
         data = round_trip(yaml)  # NOQA
 
-    def test_add_anchor(self):
+    def test_add_anchor(self) -> None:
         from ruamel.yaml.comments import CommentedMap
 
         data = CommentedMap()
@@ -246,7 +246,7 @@ class TestAnchorsAliases:
         )
 
     # this is an error in PyYAML
-    def test_reused_anchor(self):
+    def test_reused_anchor(self) -> None:
         from ruamel.yaml.error import ReusedAnchorWarning
 
         yaml = """
@@ -260,7 +260,7 @@ class TestAnchorsAliases:
         with pytest.warns(ReusedAnchorWarning):
             data = round_trip(yaml)  # NOQA
 
-    def test_issue_130(self):
+    def test_issue_130(self) -> None:
         # issue 130 reported by Devid Fee
         import ruamel.yaml
 
@@ -285,7 +285,7 @@ class TestAnchorsAliases:
         data = yaml.load(ys)
         assert data['services']['shell']['components']['server']['port'] == 8000
 
-    def test_issue_130a(self):
+    def test_issue_130a(self) -> None:
         # issue 130 reported by Devid Fee
         import ruamel.yaml
 
@@ -331,8 +331,8 @@ class TestMergeKeysValues:
 
     # in the following d always has "expanded" the merges
 
-    def test_merge_for(self):
-        from ruamel.yaml import YAML
+    def test_merge_for(self) -> None:
+        from ruamel.yaml import YAML  # type: ignore
 
         d = YAML(typ='safe', pure=True).load(self.yaml_str)
         data = round_trip_load(self.yaml_str)
@@ -342,8 +342,8 @@ class TestMergeKeysValues:
             print(count, x)
         assert count == len(d[2])
 
-    def test_merge_keys(self):
-        from ruamel.yaml import YAML
+    def test_merge_keys(self) -> None:
+        from ruamel.yaml import YAML  # type: ignore
 
         d = YAML(typ='safe', pure=True).load(self.yaml_str)
         data = round_trip_load(self.yaml_str)
@@ -353,8 +353,8 @@ class TestMergeKeysValues:
             print(count, x)
         assert count == len(d[2])
 
-    def test_merge_values(self):
-        from ruamel.yaml import YAML
+    def test_merge_values(self) -> None:
+        from ruamel.yaml import YAML  # type: ignore
 
         d = YAML(typ='safe', pure=True).load(self.yaml_str)
         data = round_trip_load(self.yaml_str)
@@ -364,8 +364,8 @@ class TestMergeKeysValues:
             print(count, x)
         assert count == len(d[2])
 
-    def test_merge_items(self):
-        from ruamel.yaml import YAML
+    def test_merge_items(self) -> None:
+        from ruamel.yaml import YAML  # type: ignore
 
         d = YAML(typ='safe', pure=True).load(self.yaml_str)
         data = round_trip_load(self.yaml_str)
@@ -375,8 +375,8 @@ class TestMergeKeysValues:
             print(count, x)
         assert count == len(d[2])
 
-    def test_len_items_delete(self):
-        from ruamel.yaml import YAML
+    def test_len_items_delete(self) -> None:
+        from ruamel.yaml import YAML  # type: ignore
 
         d = YAML(typ='safe', pure=True).load(self.yaml_str)
         data = round_trip_load(self.yaml_str)
@@ -395,8 +395,8 @@ class TestMergeKeysValues:
         ref -= 1
         assert len(x) == ref
 
-    def test_issue_196_cast_of_dict(self, capsys):
-        from ruamel.yaml import YAML
+    def test_issue_196_cast_of_dict(self, capsys: Any) -> None:
+        from ruamel.yaml import YAML  # type: ignore
 
         yaml = YAML()
         mapping = yaml.load("""\
@@ -433,15 +433,15 @@ class TestMergeKeysValues:
         assert 'a' in dict(mapping)
         assert 'a' in dict(mapping.items())
 
-    def test_values_of_merged(self):
-        from ruamel.yaml import YAML
+    def test_values_of_merged(self) -> None:
+        from ruamel.yaml import YAML  # type: ignore
 
         yaml = YAML()
         data = yaml.load(dedent(self.yaml_str))
         assert list(data[2].values()) == [1, 6, 'x2', 'x3', 'y4']
 
-    def test_issue_213_copy_of_merge(self):
-        from ruamel.yaml import YAML
+    def test_issue_213_copy_of_merge(self) -> None:
+        from ruamel.yaml import YAML  # type: ignore
 
         yaml = YAML()
         d = yaml.load("""\
@@ -461,9 +461,9 @@ class TestMergeKeysValues:
 
 
 class TestDuplicateKeyThroughAnchor:
-    def test_duplicate_key_00(self):
+    def test_duplicate_key_00(self) -> None:
         from ruamel.yaml import version_info
-        from ruamel.yaml import YAML
+        from ruamel.yaml import YAML  # type: ignore
         from ruamel.yaml.constructor import DuplicateKeyFutureWarning, DuplicateKeyError
 
         s = dedent("""\
@@ -486,7 +486,7 @@ class TestDuplicateKeyThroughAnchor:
             with pytest.raises(DuplicateKeyError):
                 YAML(typ='rt').load(s)
 
-    def test_duplicate_key_01(self):
+    def test_duplicate_key_01(self) -> None:
         # so issue https://stackoverflow.com/a/52852106/1307905
         from ruamel.yaml import version_info
         from ruamel.yaml.constructor import DuplicateKeyError
@@ -511,7 +511,7 @@ class TestDuplicateKeyThroughAnchor:
 
 
 class TestFullCharSetAnchors:
-    def test_master_of_orion(self):
+    def test_master_of_orion(self) -> None:
         # https://bitbucket.org/ruamel/yaml/issues/72/not-allowed-in-anchor-names
         # submitted by Shalon Wood
         yaml_str = """
@@ -522,7 +522,7 @@ class TestFullCharSetAnchors:
         """
         data = load(yaml_str)  # NOQA
 
-    def test_roundtrip_00(self):
+    def test_roundtrip_00(self) -> None:
         yaml_str = """
         - &dotted.words.here
           a: 1
@@ -531,7 +531,7 @@ class TestFullCharSetAnchors:
         """
         data = round_trip(yaml_str)  # NOQA
 
-    def test_roundtrip_01(self):
+    def test_roundtrip_01(self) -> None:
         yaml_str = """
         - &dotted.words.here[a, b]
         - *dotted.words.here
diff --git a/_test/test_api_change.py b/_test/test_api_change.py
index 22250b8..8961273 100644
--- a/_test/test_api_change.py
+++ b/_test/test_api_change.py
@@ -6,12 +6,14 @@ testing of anchors and the aliases referring to them
 
 import sys
 import textwrap
-import pytest
+import pytest  # type: ignore
 from pathlib import Path
 
+from typing import Any
+
 
 class TestNewAPI:
-    def test_duplicate_keys_00(self):
+    def test_duplicate_keys_00(self) -> None:
         from ruamel.yaml import YAML
         from ruamel.yaml.constructor import DuplicateKeyError
 
@@ -19,7 +21,7 @@ class TestNewAPI:
         with pytest.raises(DuplicateKeyError):
             yaml.load('{a: 1, a: 2}')
 
-    def test_duplicate_keys_01(self):
+    def test_duplicate_keys_01(self) -> None:
         from ruamel.yaml import YAML
         from ruamel.yaml.constructor import DuplicateKeyError
 
@@ -27,7 +29,7 @@ class TestNewAPI:
         with pytest.raises(DuplicateKeyError):
             yaml.load('{a: 1, a: 2}')
 
-    def test_duplicate_keys_02(self):
+    def test_duplicate_keys_02(self) -> None:
         from ruamel.yaml import YAML
         from ruamel.yaml.constructor import DuplicateKeyError
 
@@ -35,7 +37,7 @@ class TestNewAPI:
         with pytest.raises(DuplicateKeyError):
             yaml.load('{a: 1, a: 2}')
 
-    def test_issue_135(self):
+    def test_issue_135(self) -> None:
         # reported by Andrzej Ostrowski
         from ruamel.yaml import YAML
 
@@ -44,7 +46,7 @@ class TestNewAPI:
         # originally on 2.7: with pytest.raises(TypeError):
         yaml.dump(data, sys.stdout)
 
-    def test_issue_135_temporary_workaround(self):
+    def test_issue_135_temporary_workaround(self) -> None:
         # never raised error
         from ruamel.yaml import YAML
 
@@ -54,7 +56,7 @@ class TestNewAPI:
 
 
 class TestWrite:
-    def test_dump_path(self, tmpdir):
+    def test_dump_path(self, tmpdir: Any) -> None:
         from ruamel.yaml import YAML
 
         fn = Path(str(tmpdir)) / 'test.yaml'
@@ -65,7 +67,7 @@ class TestWrite:
         yaml.dump(data, fn)
         assert fn.read_text() == 'a: 1\nb: 2\n'
 
-    def test_dump_file(self, tmpdir):
+    def test_dump_file(self, tmpdir: Any) -> None:
         from ruamel.yaml import YAML
 
         fn = Path(str(tmpdir)) / 'test.yaml'
@@ -77,7 +79,7 @@ class TestWrite:
             yaml.dump(data, fp)
         assert fn.read_text() == 'a: 1\nb: 2\n'
 
-    def test_dump_missing_stream(self):
+    def test_dump_missing_stream(self) -> None:
         from ruamel.yaml import YAML
 
         yaml = YAML()
@@ -87,7 +89,7 @@ class TestWrite:
         with pytest.raises(TypeError):
             yaml.dump(data)
 
-    def test_dump_too_many_args(self, tmpdir):
+    def test_dump_too_many_args(self, tmpdir: Any) -> None:
         from ruamel.yaml import YAML
 
         fn = Path(str(tmpdir)) / 'test.yaml'
@@ -96,12 +98,12 @@ class TestWrite:
         data['a'] = 1
         data['b'] = 2
         with pytest.raises(TypeError):
-            yaml.dump(data, fn, True)
+            yaml.dump(data, fn, True)  # type: ignore
 
-    def test_transform(self, tmpdir):
+    def test_transform(self, tmpdir: Any) -> None:
         from ruamel.yaml import YAML
 
-        def tr(s):
+        def tr(s: str) -> str:
             return s.replace(' ', '  ')
 
         fn = Path(str(tmpdir)) / 'test.yaml'
@@ -112,7 +114,7 @@ class TestWrite:
         yaml.dump(data, fn, transform=tr)
         assert fn.read_text() == 'a:  1\nb:  2\n'
 
-    def test_print(self, capsys):
+    def test_print(self, capsys: Any) -> None:
         from ruamel.yaml import YAML
 
         yaml = YAML()
@@ -125,7 +127,7 @@ class TestWrite:
 
 
 class TestRead:
-    def test_multi_load(self):
+    def test_multi_load(self) -> None:
         # make sure reader, scanner, parser get reset
         from ruamel.yaml import YAML
 
@@ -133,7 +135,7 @@ class TestRead:
         yaml.load('a: 1')
         yaml.load('a: 1')  # did not work in 0.15.4
 
-    def test_parse(self):
+    def test_parse(self) -> None:
         # ensure `parse` method is functional and can parse "unsafe" yaml
         from ruamel.yaml import YAML
         from ruamel.yaml.constructor import ConstructorError
@@ -150,7 +152,7 @@ class TestRead:
 
 
 class TestLoadAll:
-    def test_multi_document_load(self, tmpdir):
+    def test_multi_document_load(self, tmpdir: Any) -> None:
         """this went wrong on 3.7 because of StopIteration, PR 37 and Issue 211"""
         from ruamel.yaml import YAML
 
@@ -169,7 +171,7 @@ class TestLoadAll:
 
 
 class TestDuplSet:
-    def test_dupl_set_00(self):
+    def test_dupl_set_00(self) -> None:
         # round-trip-loader should except
         from ruamel.yaml import YAML
         from ruamel.yaml.constructor import DuplicateKeyError
@@ -190,7 +192,7 @@ class TestDuplSet:
 class TestDumpLoadUnicode:
     # test triggered by SamH on stackoverflow (https://stackoverflow.com/q/45281596/1307905)
     # and answer by randomir (https://stackoverflow.com/a/45281922/1307905)
-    def test_write_unicode(self, tmpdir):
+    def test_write_unicode(self, tmpdir: Any) -> None:
         from ruamel.yaml import YAML
 
         yaml = YAML()
@@ -199,7 +201,7 @@ class TestDumpLoadUnicode:
         yaml.dump(text_dict, open(file_name, 'w'))
         assert open(file_name, 'rb').read().decode('utf-8') == 'text: HELLO_WORLD©\n'
 
-    def test_read_unicode(self, tmpdir):
+    def test_read_unicode(self, tmpdir: Any) -> None:
         from ruamel.yaml import YAML
 
         yaml = YAML()
@@ -211,7 +213,7 @@ class TestDumpLoadUnicode:
 
 
 class TestFlowStyle:
-    def test_flow_style(self, capsys):
+    def test_flow_style(self, capsys: Any) -> None:
         # https://stackoverflow.com/questions/45791712/
         from ruamel.yaml import YAML
 
@@ -226,8 +228,8 @@ class TestFlowStyle:
 
 
 class TestOldAPI:
-    @pytest.mark.skipif(sys.version_info >= (3, 0), reason='ok on Py3')
-    def test_duplicate_keys_02(self):
+    @pytest.mark.skipif(sys.version_info >= (3, 0), reason='ok on Py3')  # type: ignore
+    def test_duplicate_keys_02(self) -> None:
         # Issue 165 unicode keys in error/warning
         from ruamel.yaml import safe_load
         from ruamel.yaml.constructor import DuplicateKeyError
diff --git a/_test/test_class_register.py b/_test/test_class_register.py
index d996269..fdd0275 100644
--- a/_test/test_class_register.py
+++ b/_test/test_class_register.py
@@ -4,33 +4,36 @@
 testing of YAML.register_class and @yaml_object
 """
 
+from typing import Any
+from ruamel.yaml.comments import TaggedScalar, CommentedMap  # NOQA
+
 from roundtrip import YAML
 
 
-class User0(object):
-    def __init__(self, name, age):
+class User0:
+    def __init__(self, name: str, age: int) -> None:
         self.name = name
         self.age = age
 
 
-class User1(object):
+class User1:
     yaml_tag = '!user'
 
-    def __init__(self, name, age):
+    def __init__(self, name: str, age: int) -> None:
         self.name = name
         self.age = age
 
     @classmethod
-    def to_yaml(cls, representer, node):
+    def to_yaml(cls, representer: Any, node: Any) -> Any:
         return representer.represent_scalar(cls.yaml_tag, '{.name}-{.age}'.format(node, node))
 
     @classmethod
-    def from_yaml(cls, constructor, node):
+    def from_yaml(cls, constructor: Any, node: Any) -> Any:
         return cls(*node.value.split('-'))
 
 
-class TestRegisterClass(object):
-    def test_register_0_rt(self):
+class TestRegisterClass:
+    def test_register_0_rt(self) -> None:
         yaml = YAML()
         yaml.register_class(User0)
         ys = """
@@ -41,7 +44,7 @@ class TestRegisterClass(object):
         d = yaml.load(ys)
         yaml.dump(d, compare=ys, unordered_lines=True)
 
-    def test_register_0_safe(self):
+    def test_register_0_safe(self) -> None:
         # default_flow_style = None
         yaml = YAML(typ='safe')
         yaml.register_class(User0)
@@ -51,7 +54,7 @@ class TestRegisterClass(object):
         d = yaml.load(ys)
         yaml.dump(d, compare=ys)
 
-    def test_register_0_unsafe(self):
+    def test_register_0_unsafe(self) -> None:
         # default_flow_style = None
         yaml = YAML(typ='unsafe')
         yaml.register_class(User0)
@@ -61,7 +64,7 @@ class TestRegisterClass(object):
         d = yaml.load(ys)
         yaml.dump(d, compare=ys)
 
-    def test_register_1_rt(self):
+    def test_register_1_rt(self) -> None:
         yaml = YAML()
         yaml.register_class(User1)
         ys = """
@@ -70,7 +73,7 @@ class TestRegisterClass(object):
         d = yaml.load(ys)
         yaml.dump(d, compare=ys)
 
-    def test_register_1_safe(self):
+    def test_register_1_safe(self) -> None:
         yaml = YAML(typ='safe')
         yaml.register_class(User1)
         ys = """
@@ -79,7 +82,7 @@ class TestRegisterClass(object):
         d = yaml.load(ys)
         yaml.dump(d, compare=ys)
 
-    def test_register_1_unsafe(self):
+    def test_register_1_unsafe(self) -> None:
         yaml = YAML(typ='unsafe')
         yaml.register_class(User1)
         ys = """
@@ -89,15 +92,15 @@ class TestRegisterClass(object):
         yaml.dump(d, compare=ys)
 
 
-class TestDecorator(object):
-    def test_decorator_implicit(self):
+class TestDecorator:
+    def test_decorator_implicit(self) -> None:
         from ruamel.yaml import yaml_object
 
         yml = YAML()
 
         @yaml_object(yml)
-        class User2(object):
-            def __init__(self, name, age):
+        class User2:
+            def __init__(self, name: str, age: int) -> None:
                 self.name = name
                 self.age = age
 
@@ -109,27 +112,27 @@ class TestDecorator(object):
         d = yml.load(ys)
         yml.dump(d, compare=ys, unordered_lines=True)
 
-    def test_decorator_explicit(self):
+    def test_decorator_explicit(self) -> None:
         from ruamel.yaml import yaml_object
 
         yml = YAML()
 
         @yaml_object(yml)
-        class User3(object):
+        class User3:
             yaml_tag = '!USER'
 
-            def __init__(self, name, age):
+            def __init__(self, name: str, age: int) -> None:
                 self.name = name
                 self.age = age
 
             @classmethod
-            def to_yaml(cls, representer, node):
+            def to_yaml(cls, representer: Any, node: Any) -> Any:
                 return representer.represent_scalar(
                     cls.yaml_tag, '{.name}-{.age}'.format(node, node)
                 )
 
             @classmethod
-            def from_yaml(cls, constructor, node):
+            def from_yaml(cls, constructor: Any, node: Any) -> Any:
                 return cls(*node.value.split('-'))
 
         ys = """
diff --git a/_test/test_collections.py b/_test/test_collections.py
index 40af9db..d6e88ef 100644
--- a/_test/test_collections.py
+++ b/_test/test_collections.py
@@ -7,14 +7,14 @@ This is now so integrated in Python that it can be mapped to !!omap
 
 """
 
-import pytest  # NOQA
+import pytest  # type: ignore  # NOQA
 
 
 from roundtrip import round_trip, dedent, round_trip_load, round_trip_dump  # NOQA
 
 
 class TestOrderedDict:
-    def test_ordereddict(self):
+    def test_ordereddict(self) -> None:
         from collections import OrderedDict
 
         assert round_trip_dump(OrderedDict()) == '!!omap []\n'
diff --git a/_test/test_comment_manipulation.py b/_test/test_comment_manipulation.py
index 6d706f2..979b386 100644
--- a/_test/test_comment_manipulation.py
+++ b/_test/test_comment_manipulation.py
@@ -1,28 +1,29 @@
 # coding: utf-8
 
-import pytest  # NOQA
+import pytest  # type: ignore  # NOQA
 
 from roundtrip import round_trip, dedent, round_trip_load, round_trip_dump  # NOQA
+from typing import Any
 
 
-def load(s):
+def load(s: str) -> Any:
     return round_trip_load(dedent(s))
 
 
-def compare(data, s, **kw):
+def compare(data: Any, s: str, **kw: Any) -> None:
     assert round_trip_dump(data, **kw) == dedent(s)
 
 
-def compare_eol(data, s):
+def compare_eol(data: Any, s: str) -> None:
     assert 'EOL' in s
     ds = dedent(s).replace('EOL', '').replace('\n', '|\n')
-    assert round_trip_dump(data).replace('\n', '|\n') == ds
+    assert round_trip_dump(data).replace('\n', '|\n') == ds  # type: ignore
 
 
 class TestCommentsManipulation:
 
     # list
-    def test_seq_set_comment_on_existing_explicit_column(self):
+    def test_seq_set_comment_on_existing_explicit_column(self) -> None:
         data = load("""
         - a   # comment 1
         - b
@@ -36,7 +37,7 @@ class TestCommentsManipulation:
         """
         compare(data, exp)
 
-    def test_seq_overwrite_comment_on_existing_explicit_column(self):
+    def test_seq_overwrite_comment_on_existing_explicit_column(self) -> None:
         data = load("""
         - a   # comment 1
         - b
@@ -50,7 +51,7 @@ class TestCommentsManipulation:
         """
         compare(data, exp)
 
-    def test_seq_first_comment_explicit_column(self):
+    def test_seq_first_comment_explicit_column(self) -> None:
         data = load("""
         - a
         - b
@@ -64,7 +65,7 @@ class TestCommentsManipulation:
         """
         compare(data, exp)
 
-    def test_seq_set_comment_on_existing_column_prev(self):
+    def test_seq_set_comment_on_existing_column_prev(self) -> None:
         data = load("""
         - a   # comment 1
         - b
@@ -80,14 +81,14 @@ class TestCommentsManipulation:
         """
         compare(data, exp)
 
-    def test_seq_set_comment_on_existing_column_next(self):
+    def test_seq_set_comment_on_existing_column_next(self) -> None:
         data = load("""
         - a   # comment 1
         - b
         - c
         - d     # comment 3
         """)
-        print(data._yaml_comment)
+        print(data.ca)
         # print(type(data._yaml_comment._items[0][0].start_mark))
         # ruamel.yaml.error.Mark
         # print(type(data._yaml_comment._items[0][0].start_mark))
@@ -100,7 +101,7 @@ class TestCommentsManipulation:
         """
         compare(data, exp)
 
-    def test_seq_set_comment_on_existing_column_further_away(self):
+    def test_seq_set_comment_on_existing_column_further_away(self) -> None:
         """
         no comment line before or after, take the latest before
         the new position
@@ -113,7 +114,7 @@ class TestCommentsManipulation:
         - e
         - f     # comment 3
         """)
-        print(data._yaml_comment)
+        print(data.ca)
         # print(type(data._yaml_comment._items[0][0].start_mark))
         # ruamel.yaml.error.Mark
         # print(type(data._yaml_comment._items[0][0].start_mark))
@@ -128,7 +129,7 @@ class TestCommentsManipulation:
         """
         compare(data, exp)
 
-    def test_seq_set_comment_on_existing_explicit_column_with_hash(self):
+    def test_seq_set_comment_on_existing_explicit_column_with_hash(self) -> None:
         data = load("""
         - a   # comment 1
         - b
@@ -144,7 +145,7 @@ class TestCommentsManipulation:
 
     # dict
 
-    def test_dict_set_comment_on_existing_explicit_column(self):
+    def test_dict_set_comment_on_existing_explicit_column(self) -> None:
         data = load("""
         a: 1   # comment 1
         b: 2
@@ -162,7 +163,7 @@ class TestCommentsManipulation:
         """
         compare(data, exp)
 
-    def test_dict_overwrite_comment_on_existing_explicit_column(self):
+    def test_dict_overwrite_comment_on_existing_explicit_column(self) -> None:
         data = load("""
         a: 1   # comment 1
         b: 2
@@ -180,7 +181,7 @@ class TestCommentsManipulation:
         """
         compare(data, exp)
 
-    def test_map_set_comment_on_existing_column_prev(self):
+    def test_map_set_comment_on_existing_column_prev(self) -> None:
         data = load("""
             a: 1   # comment 1
             b: 2
@@ -198,7 +199,7 @@ class TestCommentsManipulation:
             """
         compare(data, exp)
 
-    def test_map_set_comment_on_existing_column_next(self):
+    def test_map_set_comment_on_existing_column_next(self) -> None:
         data = load("""
             a: 1   # comment 1
             b: 2
@@ -216,7 +217,7 @@ class TestCommentsManipulation:
             """
         compare(data, exp)
 
-    def test_map_set_comment_on_existing_column_further_away(self):
+    def test_map_set_comment_on_existing_column_further_away(self) -> None:
         """
         no comment line before or after, take the latest before
         the new position
@@ -239,7 +240,7 @@ class TestCommentsManipulation:
             """
         compare(data, exp)
 
-    def test_before_top_map_rt(self):
+    def test_before_top_map_rt(self) -> None:
         data = load("""
         a: 1
         b: 2
@@ -253,7 +254,7 @@ class TestCommentsManipulation:
         """
         compare(data, exp.format(comment='#'))
 
-    def test_before_top_map_replace(self):
+    def test_before_top_map_replace(self) -> None:
         data = load("""
         # abc
         # def
@@ -269,7 +270,7 @@ class TestCommentsManipulation:
         """
         compare(data, exp.format(comment='#'))
 
-    def test_before_top_map_from_scratch(self):
+    def test_before_top_map_from_scratch(self) -> None:
         from ruamel.yaml.comments import CommentedMap
 
         data = CommentedMap()
@@ -286,7 +287,7 @@ class TestCommentsManipulation:
             """
         compare(data, exp.format(comment='#'))
 
-    def test_before_top_seq_rt(self):
+    def test_before_top_seq_rt(self) -> None:
         data = load("""
         - a
         - b
@@ -301,7 +302,7 @@ class TestCommentsManipulation:
         """
         compare(data, exp)
 
-    def test_before_top_seq_rt_replace(self):
+    def test_before_top_seq_rt_replace(self) -> None:
         s = """
         # this
         # that
@@ -319,7 +320,7 @@ class TestCommentsManipulation:
         """
         compare(data, exp.format(comment='#'))
 
-    def test_before_top_seq_from_scratch(self):
+    def test_before_top_seq_from_scratch(self) -> None:
         from ruamel.yaml.comments import CommentedSeq
 
         data = CommentedSeq()
@@ -336,7 +337,7 @@ class TestCommentsManipulation:
         compare(data, exp.format(comment='#'))
 
     # nested variants
-    def test_before_nested_map_rt(self):
+    def test_before_nested_map_rt(self) -> None:
         data = load("""
         a: 1
         b:
@@ -354,7 +355,7 @@ class TestCommentsManipulation:
         """
         compare(data, exp.format(comment='#'))
 
-    def test_before_nested_map_rt_indent(self):
+    def test_before_nested_map_rt_indent(self) -> None:
         data = load("""
         a: 1
         b:
@@ -373,7 +374,7 @@ class TestCommentsManipulation:
         compare(data, exp.format(comment='#'))
         print(data['b'].ca)
 
-    def test_before_nested_map_from_scratch(self):
+    def test_before_nested_map_from_scratch(self) -> None:
         from ruamel.yaml.comments import CommentedMap
 
         data = CommentedMap()
@@ -393,7 +394,7 @@ class TestCommentsManipulation:
         """
         compare(data, exp.format(comment='#'))
 
-    def test_before_nested_seq_from_scratch(self):
+    def test_before_nested_seq_from_scratch(self) -> None:
         from ruamel.yaml.comments import CommentedMap, CommentedSeq
 
         data = CommentedMap()
@@ -413,7 +414,7 @@ class TestCommentsManipulation:
         """
         compare(data, exp.format(comment='#'))
 
-    def test_before_nested_seq_from_scratch_block_seq_indent(self):
+    def test_before_nested_seq_from_scratch_block_seq_indent(self) -> None:
         from ruamel.yaml.comments import CommentedMap, CommentedSeq
 
         data = CommentedMap()
@@ -433,7 +434,7 @@ class TestCommentsManipulation:
         """
         compare(data, exp.format(comment='#'), indent=4, block_seq_indent=2)
 
-    def test_map_set_comment_before_and_after_non_first_key_00(self):
+    def test_map_set_comment_before_and_after_non_first_key_00(self) -> None:
         # http://stackoverflow.com/a/40705671/1307905
         data = load("""
         xyz:
@@ -462,7 +463,7 @@ class TestCommentsManipulation:
         """
         compare(data, exp)
 
-    def Xtest_map_set_comment_before_and_after_non_first_key_01(self):
+    def Xtest_map_set_comment_before_and_after_non_first_key_01(self) -> None:
         data = load("""
         xyz:
           a: 1    # comment 1
@@ -494,7 +495,7 @@ class TestCommentsManipulation:
 
     # EOL is no longer necessary
     # fixed together with issue # 216
-    def test_map_set_comment_before_and_after_non_first_key_01(self):
+    def test_map_set_comment_before_and_after_non_first_key_01(self) -> None:
         data = load("""
         xyz:
           a: 1    # comment 1
@@ -523,7 +524,7 @@ class TestCommentsManipulation:
         """
         compare(data, exp)
 
-    def Xtest_map_set_comment_before_and_after_non_first_key_02(self):
+    def Xtest_map_set_comment_before_and_after_non_first_key_02(self) -> None:
         data = load("""
         xyz:
           a: 1    # comment 1
@@ -555,7 +556,7 @@ class TestCommentsManipulation:
         """
         compare_eol(data, exp)
 
-    def test_map_set_comment_before_and_after_non_first_key_02(self):
+    def test_map_set_comment_before_and_after_non_first_key_02(self) -> None:
         data = load("""
         xyz:
           a: 1    # comment 1
diff --git a/_test/test_comments.py b/_test/test_comments.py
index dbf035d..64b8cd2 100644
--- a/_test/test_comments.py
+++ b/_test/test_comments.py
@@ -10,14 +10,14 @@ roundtrip changes
 
 """
 
-import pytest
+import pytest  # type: ignore  # NOQA
 import sys
 
 from roundtrip import round_trip, dedent, round_trip_load, round_trip_dump
 
 
 class TestComments:
-    def test_no_end_of_file_eol(self):
+    def test_no_end_of_file_eol(self) -> None:
         """not excluding comments caused some problems if at the end of
         the file without a newline. First error, then included \0 """
         x = """\
@@ -26,7 +26,7 @@ class TestComments:
         with pytest.raises(AssertionError):
             round_trip(x, extra='a\n')
 
-    def test_no_comments(self):
+    def test_no_comments(self) -> None:
         round_trip("""
         - europe: 10
         - usa:
@@ -34,7 +34,7 @@ class TestComments:
           - california: 9
         """)
 
-    def test_round_trip_ordering(self):
+    def test_round_trip_ordering(self) -> None:
         round_trip("""
         a: 1
         b: 2
@@ -46,7 +46,7 @@ class TestComments:
         f: 6
         """)
 
-    def test_complex(self):
+    def test_complex(self) -> None:
         round_trip("""
         - europe: 10 # top
         - usa:
@@ -54,7 +54,7 @@ class TestComments:
           - california: 9 # o
         """)
 
-    def test_dropped(self):
+    def test_dropped(self) -> None:
         s = """\
         # comment
         scalar
@@ -62,7 +62,7 @@ class TestComments:
         """
         round_trip(s, 'scalar\n...\n')
 
-    def test_main_mapping_begin_end(self):
+    def test_main_mapping_begin_end(self) -> None:
         round_trip("""
         # C start a
         # C start b
@@ -73,7 +73,7 @@ class TestComments:
         # C end b
         """)
 
-    def test_reindent(self):
+    def test_reindent(self) -> None:
         x = """\
         a:
           b:     # comment 1
@@ -87,7 +87,7 @@ class TestComments:
                 c: 1 # comment 2
         """)
 
-    def test_main_mapping_begin_end_items_post(self):
+    def test_main_mapping_begin_end_items_post(self) -> None:
         round_trip("""
         # C start a
         # C start b
@@ -98,7 +98,7 @@ class TestComments:
         # C end b
         """)
 
-    def test_main_sequence_begin_end(self):
+    def test_main_sequence_begin_end(self) -> None:
         round_trip("""
         # C start a
         # C start b
@@ -109,7 +109,7 @@ class TestComments:
         # C end b
         """)
 
-    def test_main_sequence_begin_end_items_post(self):
+    def test_main_sequence_begin_end_items_post(self) -> None:
         round_trip("""
         # C start a
         # C start b
@@ -120,7 +120,7 @@ class TestComments:
         # C end b
         """)
 
-    def test_main_mapping_begin_end_complex(self):
+    def test_main_mapping_begin_end_complex(self) -> None:
         round_trip("""
         # C start a
         # C start b
@@ -133,7 +133,7 @@ class TestComments:
         # C end b
         """)
 
-    def test_09(self):  # 2.9 from the examples in the spec
+    def test_09(self) -> None:  # 2.9 from the examples in the spec
         s = """\
         hr: # 1998 hr ranking
           - Mark McGwire
@@ -145,7 +145,7 @@ class TestComments:
         """
         round_trip(s, indent=4, block_seq_indent=2)
 
-    def test_09a(self):
+    def test_09a(self) -> None:
         round_trip("""
         hr: # 1998 hr ranking
         - Mark McGwire
@@ -156,7 +156,7 @@ class TestComments:
         - Ken Griffey
         """)
 
-    def test_simple_map_middle_comment(self):
+    def test_simple_map_middle_comment(self) -> None:
         round_trip("""
         abc: 1
         # C 3a
@@ -164,7 +164,7 @@ class TestComments:
         ghi: 2
         """)
 
-    def test_map_in_map_0(self):
+    def test_map_in_map_0(self) -> None:
         round_trip("""
         map1: # comment 1
           # comment 2
@@ -172,7 +172,7 @@ class TestComments:
             key1: val1
         """)
 
-    def test_map_in_map_1(self):
+    def test_map_in_map_1(self) -> None:
         # comment is moved from value to key
         round_trip("""
         map1:
@@ -181,7 +181,7 @@ class TestComments:
             key1: val1
         """)
 
-    def test_application_arguments(self):
+    def test_application_arguments(self) -> None:
         # application configur
         round_trip("""
         args:
@@ -194,7 +194,7 @@ class TestComments:
             wait: 10
         """)
 
-    def test_substitute(self):
+    def test_substitute(self) -> None:
         x = """
         args:
           username: anthon          # name
@@ -211,7 +211,7 @@ class TestComments:
         x = x.replace(': secret          ', ': deleted password')
         assert round_trip_dump(data) == dedent(x)
 
-    def test_set_comment(self):
+    def test_set_comment(self) -> None:
         round_trip("""
         !!set
         # the beginning
@@ -222,7 +222,7 @@ class TestComments:
         # this is the end
         """)
 
-    def test_omap_comment_roundtrip(self):
+    def test_omap_comment_roundtrip(self) -> None:
         round_trip("""
         !!omap
         - a: 1
@@ -231,7 +231,7 @@ class TestComments:
         - d: 4
         """)
 
-    def test_omap_comment_roundtrip_pre_comment(self):
+    def test_omap_comment_roundtrip_pre_comment(self) -> None:
         round_trip("""
         !!omap
         - a: 1
@@ -241,7 +241,7 @@ class TestComments:
         - d: 4
         """)
 
-    def test_non_ascii(self):
+    def test_non_ascii(self) -> None:
         round_trip("""
         verbosity: 1                  # 0 is minimal output, -1 none
         base_url: http://gopher.net
@@ -263,7 +263,7 @@ class TestComments:
             Italy: Rome
         """)
 
-    def test_dump_utf8(self):
+    def test_dump_utf8(self) -> None:
         import ruamel.yaml  # NOQA
 
         x = dedent("""\
@@ -278,7 +278,7 @@ class TestComments:
             )
             assert y == x
 
-    def test_dump_unicode_utf8(self):
+    def test_dump_unicode_utf8(self) -> None:
         import ruamel.yaml  # NOQA
 
         x = dedent("""\
@@ -293,7 +293,7 @@ class TestComments:
             )
             assert y == x
 
-    def test_mlget_00(self):
+    def test_mlget_00(self) -> None:
         x = """\
         a:
         - b:
@@ -314,7 +314,7 @@ class TestInsertPopList:
     need to move the values to subsequent keys on insert"""
 
     @property
-    def ins(self):
+    def ins(self) -> str:
         return """\
         ab:
         - a      # a
@@ -327,7 +327,7 @@ class TestInsertPopList:
         - 2
         """
 
-    def test_insert_0(self):
+    def test_insert_0(self) -> None:
         d = round_trip_load(self.ins)
         d['ab'].insert(0, 'xyz')
         y = round_trip_dump(d, indent=2)
@@ -344,7 +344,7 @@ class TestInsertPopList:
         - 2
         """)
 
-    def test_insert_1(self):
+    def test_insert_1(self) -> None:
         d = round_trip_load(self.ins)
         d['ab'].insert(4, 'xyz')
         y = round_trip_dump(d, indent=2)
@@ -361,7 +361,7 @@ class TestInsertPopList:
         - 2
         """)
 
-    def test_insert_2(self):
+    def test_insert_2(self) -> None:
         d = round_trip_load(self.ins)
         d['ab'].insert(1, 'xyz')
         y = round_trip_dump(d, indent=2)
@@ -378,7 +378,7 @@ class TestInsertPopList:
         - 2
         """)
 
-    def test_pop_0(self):
+    def test_pop_0(self) -> None:
         d = round_trip_load(self.ins)
         d['ab'].pop(0)
         y = round_trip_dump(d, indent=2)
@@ -394,7 +394,7 @@ class TestInsertPopList:
         - 2
         """)
 
-    def test_pop_1(self):
+    def test_pop_1(self) -> None:
         d = round_trip_load(self.ins)
         d['ab'].pop(1)
         y = round_trip_dump(d, indent=2)
@@ -410,7 +410,7 @@ class TestInsertPopList:
         - 2
         """)
 
-    def test_pop_2(self):
+    def test_pop_2(self) -> None:
         d = round_trip_load(self.ins)
         d['ab'].pop(2)
         y = round_trip_dump(d, indent=2)
@@ -426,7 +426,7 @@ class TestInsertPopList:
         - 2
         """)
 
-    def test_pop_3(self):
+    def test_pop_3(self) -> None:
         d = round_trip_load(self.ins)
         d['ab'].pop(3)
         y = round_trip_dump(d, indent=2)
@@ -446,14 +446,14 @@ class TestInsertPopList:
 # http://stackoverflow.com/a/36970608/1307905
 class TestInsertInMapping:
     @property
-    def ins(self):
+    def ins(self) -> str:
         return """\
         first_name: Art
         occupation: Architect  # This is an occupation comment
         about: Art Vandelay is a fictional character that George invents...
         """
 
-    def test_insert_at_pos_1(self):
+    def test_insert_at_pos_1(self) -> None:
         d = round_trip_load(self.ins)
         d.insert(1, 'last name', 'Vandelay', comment='new key')
         y = round_trip_dump(d)
@@ -465,7 +465,7 @@ class TestInsertInMapping:
         about: Art Vandelay is a fictional character that George invents...
         """)
 
-    def test_insert_at_pos_0(self):
+    def test_insert_at_pos_0(self) -> None:
         d = round_trip_load(self.ins)
         d.insert(0, 'last name', 'Vandelay', comment='new key')
         y = round_trip_dump(d)
@@ -477,7 +477,7 @@ class TestInsertInMapping:
         about: Art Vandelay is a fictional character that George invents...
         """)
 
-    def test_insert_at_pos_3(self):
+    def test_insert_at_pos_3(self) -> None:
         # much more simple if done with appending.
         d = round_trip_load(self.ins)
         d.insert(3, 'last name', 'Vandelay', comment='new key')
@@ -492,7 +492,7 @@ class TestInsertInMapping:
 
 
 class TestCommentedMapMerge:
-    def test_in_operator(self):
+    def test_in_operator(self) -> None:
         data = round_trip_load("""
         x: &base
           a: 1
@@ -508,7 +508,7 @@ class TestCommentedMapMerge:
         assert data['y']['a'] == 1
         assert 'a' in data['y']
 
-    def test_issue_60(self):
+    def test_issue_60(self) -> None:
         data = round_trip_load("""
         x: &base
           a: 1
@@ -519,7 +519,7 @@ class TestCommentedMapMerge:
         assert data['y']['a'] == 1
         assert str(data['y']) == """ordereddict([('a', 1)])"""
 
-    def test_issue_60_1(self):
+    def test_issue_60_1(self) -> None:
         data = round_trip_load("""
         x: &base
           a: 1
@@ -534,7 +534,7 @@ class TestCommentedMapMerge:
 
 class TestEmptyLines:
     # prompted by issue 46 from Alex Harvey
-    def test_issue_46(self):
+    def test_issue_46(self) -> None:
         yaml_str = dedent("""\
         ---
         # Please add key/value pairs in alphabetical order
@@ -549,7 +549,7 @@ class TestEmptyLines:
         y = round_trip_dump(d, explicit_start=True)
         assert yaml_str == y
 
-    def test_multispace_map(self):
+    def test_multispace_map(self) -> None:
         round_trip("""
         a: 1x
 
@@ -564,8 +564,8 @@ class TestEmptyLines:
 
         """)
 
-    @pytest.mark.xfail(strict=True)
-    def test_multispace_map_initial(self):
+    @pytest.mark.xfail(strict=True)  # type: ignore
+    def test_multispace_map_initial(self) -> None:
         round_trip("""
 
         a: 1x
@@ -581,7 +581,7 @@ class TestEmptyLines:
 
         """)
 
-    def test_embedded_map(self):
+    def test_embedded_map(self) -> None:
         round_trip("""
         - a: 1y
           b: 2y
@@ -589,7 +589,7 @@ class TestEmptyLines:
           c: 3y
         """)
 
-    def test_toplevel_seq(self):
+    def test_toplevel_seq(self) -> None:
         round_trip("""\
         - 1
 
@@ -598,7 +598,7 @@ class TestEmptyLines:
         - 3
         """)
 
-    def test_embedded_seq(self):
+    def test_embedded_seq(self) -> None:
         round_trip("""
         a:
           b:
@@ -610,7 +610,7 @@ class TestEmptyLines:
           - 3
         """)
 
-    def test_line_with_only_spaces(self):
+    def test_line_with_only_spaces(self) -> None:
         # issue 54
         yaml_str = "---\n\na: 'x'\n \nb: y\n"
         d = round_trip_load(yaml_str, preserve_quotes=True)
@@ -621,7 +621,7 @@ class TestEmptyLines:
             print(line + '$')
         assert stripped == y
 
-    def test_some_eol_spaces(self):
+    def test_some_eol_spaces(self) -> None:
         # spaces after tokens and on empty lines
         yaml_str = '---  \n  \na: "x"  \n   \nb: y  \n'
         d = round_trip_load(yaml_str, preserve_quotes=True)
@@ -632,7 +632,7 @@ class TestEmptyLines:
             print(line + '$')
         assert stripped == y
 
-    def test_issue_54_not_ok(self):
+    def test_issue_54_not_ok(self) -> None:
         yaml_str = dedent("""\
         toplevel:
 
@@ -642,10 +642,11 @@ class TestEmptyLines:
         d = round_trip_load(yaml_str)
         print(d.ca)
         y = round_trip_dump(d, indent=4)
+        assert isinstance(y, str)
         print(y.replace('\n', '$\n'))
         assert yaml_str == y
 
-    def test_issue_54_ok(self):
+    def test_issue_54_ok(self) -> None:
         yaml_str = dedent("""\
         toplevel:
             # some comment
@@ -655,7 +656,7 @@ class TestEmptyLines:
         y = round_trip_dump(d, indent=4)
         assert yaml_str == y
 
-    def test_issue_93(self):
+    def test_issue_93(self) -> None:
         round_trip("""\
         a:
           b:
@@ -664,7 +665,7 @@ class TestEmptyLines:
           - c2: catfish  # a2
         """)
 
-    def test_issue_93_00(self):
+    def test_issue_93_00(self) -> None:
         round_trip("""\
         a:
         - - c1: cat   # a1
@@ -672,14 +673,14 @@ class TestEmptyLines:
           - c2: catfish  # a2
         """)
 
-    def test_issue_93_01(self):
+    def test_issue_93_01(self) -> None:
         round_trip("""\
         - - c1: cat   # a1
           # my comment on catfish
           - c2: catfish  # a2
         """)
 
-    def test_issue_93_02(self):
+    def test_issue_93_02(self) -> None:
         # never failed as there is no indent
         round_trip("""\
         - c1: cat
@@ -687,7 +688,7 @@ class TestEmptyLines:
         - c2: catfish
         """)
 
-    def test_issue_96(self):
+    def test_issue_96(self) -> None:
         # inserted extra line on trailing spaces
         round_trip("""\
         a:
@@ -701,8 +702,8 @@ class TestEmptyLines:
 
 
 class TestUnicodeComments:
-    @pytest.mark.skipif(sys.version_info < (2, 7), reason='wide unicode')
-    def test_issue_55(self):  # reported by Haraguroicha Hsu
+    @pytest.mark.skipif(sys.version_info < (2, 7), reason='wide unicode')  # type: ignore
+    def test_issue_55(self) -> None:  # reported by Haraguroicha Hsu
         round_trip("""\
         name: TEST
         description: test using
@@ -722,7 +723,7 @@ class TestUnicodeComments:
 
 
 class TestEmptyValueBeforeComments:
-    def test_issue_25a(self):
+    def test_issue_25a(self) -> None:
         round_trip("""\
         - a: b
           c: d
@@ -730,7 +731,7 @@ class TestEmptyValueBeforeComments:
           - e: f
         """)
 
-    def test_issue_25a1(self):
+    def test_issue_25a1(self) -> None:
         round_trip("""\
         - a: b
           c: d
@@ -738,13 +739,13 @@ class TestEmptyValueBeforeComments:
             e: f
         """)
 
-    def test_issue_25b(self):
+    def test_issue_25b(self) -> None:
         round_trip("""\
         var1: #empty
         var2: something #notempty
         """)
 
-    def test_issue_25c(self):
+    def test_issue_25c(self) -> None:
         round_trip("""\
         params:
           a: 1 # comment a
@@ -752,7 +753,7 @@ class TestEmptyValueBeforeComments:
           c: 3 # comment c
         """)
 
-    def test_issue_25c1(self):
+    def test_issue_25c1(self) -> None:
         round_trip("""\
         params:
           a: 1 # comment a
@@ -761,14 +762,14 @@ class TestEmptyValueBeforeComments:
           c: 3 # comment c
         """)
 
-    def test_issue_25_00(self):
+    def test_issue_25_00(self) -> None:
         round_trip("""\
         params:
           a: 1 # comment a
           b:   # comment b
         """)
 
-    def test_issue_25_01(self):
+    def test_issue_25_01(self) -> None:
         round_trip("""\
         a:        # comment 1
                   #  comment 2
@@ -776,14 +777,14 @@ class TestEmptyValueBeforeComments:
             c: 1  #    comment 4
         """)
 
-    def test_issue_25_02(self):
+    def test_issue_25_02(self) -> None:
         round_trip("""\
         a:        # comment 1
                   #  comment 2
         - b: 2    #   comment 3
         """)
 
-    def test_issue_25_03(self):
+    def test_issue_25_03(self) -> None:
         s = """\
         a:        # comment 1
                   #  comment 2
@@ -791,14 +792,14 @@ class TestEmptyValueBeforeComments:
         """
         round_trip(s, indent=4, block_seq_indent=2)
 
-    def test_issue_25_04(self):
+    def test_issue_25_04(self) -> None:
         round_trip("""\
         a:        # comment 1
                   #  comment 2
           b: 1    #   comment 3
         """)
 
-    def test_flow_seq_within_seq(self):
+    def test_flow_seq_within_seq(self) -> None:
         round_trip("""\
         # comment 1
         - a
@@ -813,7 +814,7 @@ class TestEmptyValueBeforeComments:
         - []
         """)
 
-    def test_comment_after_block_scalar_indicator(self):
+    def test_comment_after_block_scalar_indicator(self) -> None:
         round_trip("""\
         a: | # abc
           test 1
@@ -834,7 +835,7 @@ a: |
 
 class TestBlockScalarWithComments:
     # issue 99 reported by Colm O'Connor
-    def test_scalar_with_comments(self):
+    def test_scalar_with_comments(self) -> None:
         import ruamel.yaml  # NOQA
 
         for x in [
diff --git a/_test/test_contextmanager.py b/_test/test_contextmanager.py
index bdc8b78..e6256d3 100644
--- a/_test/test_contextmanager.py
+++ b/_test/test_contextmanager.py
@@ -5,8 +5,9 @@ testing of anchors and the aliases referring to them
 """
 
 import sys
-import pytest
+import pytest  # type: ignore
 
+from typing import Any
 
 single_doc = """\
 - a: 1
@@ -31,33 +32,33 @@ multi_doc = """\
 multi_doc_data = [['abc', 'xyz'], single_data]
 
 
-def get_yaml():
+def get_yaml() -> Any:
     from ruamel.yaml import YAML
 
     return YAML()
 
 
 class TestOldStyle:
-    def test_single_load(self):
+    def test_single_load(self) -> None:
         d = get_yaml().load(single_doc)
         print(d)
         print(type(d[0]))
         assert d == single_data
 
-    def test_single_load_no_arg(self):
+    def test_single_load_no_arg(self) -> None:
         with pytest.raises(TypeError):
             assert get_yaml().load() == single_data
 
-    def test_multi_load(self):
+    def test_multi_load(self) -> None:
         data = list(get_yaml().load_all(multi_doc))
         assert data == multi_doc_data
 
-    def test_single_dump(self, capsys):
+    def test_single_dump(self, capsys: Any) -> None:
         get_yaml().dump(single_data, sys.stdout)
         out, err = capsys.readouterr()
         assert out == single_doc
 
-    def test_multi_dump(self, capsys):
+    def test_multi_dump(self, capsys: Any) -> None:
         yaml = get_yaml()
         yaml.explicit_start = True
         yaml.dump_all(multi_doc_data, sys.stdout)
@@ -66,7 +67,7 @@ class TestOldStyle:
 
 
 class TestContextManager:
-    def test_single_dump(self, capsys):
+    def test_single_dump(self, capsys: Any) -> None:
         from ruamel.yaml import YAML
 
         with YAML(output=sys.stdout) as yaml:
@@ -75,7 +76,7 @@ class TestContextManager:
         print(err)
         assert out == single_doc
 
-    def test_multi_dump(self, capsys):
+    def test_multi_dump(self, capsys: Any) -> None:
         from ruamel.yaml import YAML
 
         with YAML(output=sys.stdout) as yaml:
@@ -103,7 +104,7 @@ class TestContextManager:
     #         for idx, data in enumerate(yaml.load()):
     #             assert data == multi_doc_data[0]
 
-    def test_roundtrip(self, capsys):
+    def test_roundtrip(self, capsys: Any) -> None:
         from ruamel.yaml import YAML
 
         with YAML(output=sys.stdout) as yaml:
diff --git a/_test/test_copy.py b/_test/test_copy.py
index 4931d2a..cf402a4 100644
--- a/_test/test_copy.py
+++ b/_test/test_copy.py
@@ -6,13 +6,13 @@ Testing copy and deepcopy, instigated by Issue 84 (Peter Amstutz)
 
 import copy
 
-import pytest  # NOQA
+import pytest  # type: ignore  # NOQA
 
 from roundtrip import dedent, round_trip_load, round_trip_dump
 
 
 class TestDeepCopy:
-    def test_preserve_flow_style_simple(self):
+    def test_preserve_flow_style_simple(self) -> None:
         x = dedent("""\
         {foo: bar, baz: quux}
         """)
@@ -24,7 +24,7 @@ class TestDeepCopy:
         assert y == x
         assert data.fa.flow_style() == data_copy.fa.flow_style()
 
-    def test_deepcopy_flow_style_nested_dict(self):
+    def test_deepcopy_flow_style_nested_dict(self) -> None:
         x = dedent("""\
         a: {foo: bar, baz: quux}
         """)
@@ -46,7 +46,7 @@ class TestDeepCopy:
           baz: quux
         """)
 
-    def test_deepcopy_flow_style_nested_list(self):
+    def test_deepcopy_flow_style_nested_list(self) -> None:
         x = dedent("""\
         a: [1, 2, 3]
         """)
@@ -71,7 +71,7 @@ class TestDeepCopy:
 
 
 class TestCopy:
-    def test_copy_flow_style_nested_dict(self):
+    def test_copy_flow_style_nested_dict(self) -> None:
         x = dedent("""\
         a: {foo: bar, baz: quux}
         """)
@@ -93,7 +93,7 @@ class TestCopy:
           baz: quux
         """)
 
-    def test_copy_flow_style_nested_list(self):
+    def test_copy_flow_style_nested_list(self) -> None:
         x = dedent("""\
         a: [1, 2, 3]
         """)
diff --git a/_test/test_cyaml.py b/_test/test_cyaml.py
index 593d171..056093b 100644
--- a/_test/test_cyaml.py
+++ b/_test/test_cyaml.py
@@ -2,17 +2,17 @@
 
 import sys
 import platform
-import pytest
+import pytest  # type: ignore  # NOQA
 from textwrap import dedent
 
 NO_CLIB_VER = (3, 10)
 
 
-@pytest.mark.skipif(
+@pytest.mark.skipif(  # type: ignore
     platform.python_implementation() in ['Jython', 'PyPy'],
     reason='Jython throws RepresenterError'
 )
-def test_load_cyaml():
+def test_load_cyaml() -> None:
     print("???????????????????????", platform.python_implementation())
     import ruamel.yaml
 
@@ -24,10 +24,10 @@ def test_load_cyaml():
     yaml.load('abc: 1')
 
 
-@pytest.mark.skipif(sys.version_info >= NO_CLIB_VER
+@pytest.mark.skipif(sys.version_info >= NO_CLIB_VER  # type: ignore
                     or platform.python_implementation() in ['Jython', 'PyPy'],
                     reason='no _PyGC_FINALIZED')
-def test_dump_cyaml():
+def test_dump_cyaml() -> None:
     import ruamel.yaml
 
     if sys.version_info >= NO_CLIB_VER:
@@ -41,10 +41,10 @@ def test_dump_cyaml():
     assert buf.getvalue() == 'a: 1\nb: 2\n'
 
 
-@pytest.mark.skipif(
+@pytest.mark.skipif(  # type: ignore
     platform.python_implementation() in ['Jython', 'PyPy'], reason='not avialable'
 )
-def test_load_cyaml_1_2():
+def test_load_cyaml_1_2() -> None:
     # issue 155
     import ruamel.yaml
 
@@ -60,10 +60,10 @@ def test_load_cyaml_1_2():
     yaml.load(inp)
 
 
-@pytest.mark.skipif(
+@pytest.mark.skipif(  # type: ignore
     platform.python_implementation() in ['Jython', 'PyPy'], reason='not available'
 )
-def test_dump_cyaml_1_2():
+def test_dump_cyaml_1_2() -> None:
     # issue 155
     import ruamel.yaml
     from ruamel.yaml.compat import StringIO
diff --git a/_test/test_datetime.py b/_test/test_datetime.py
index 7321816..bc86e74 100644
--- a/_test/test_datetime.py
+++ b/_test/test_datetime.py
@@ -20,13 +20,13 @@ Please note that a fraction can only be included if not equal to 0
 """
 
 import copy
-import pytest  # NOQA
+import pytest  # type: ignore  # NOQA
 
 from roundtrip import round_trip, dedent, round_trip_load, round_trip_dump  # NOQA
 
 
 class TestDateTime:
-    def test_date_only(self):
+    def test_date_only(self) -> None:
         inp = """
         - 2011-10-02
         """
@@ -35,7 +35,7 @@ class TestDateTime:
         """
         round_trip(inp, exp)
 
-    def test_zero_fraction(self):
+    def test_zero_fraction(self) -> None:
         inp = """
         - 2011-10-02 16:45:00.0
         """
@@ -44,7 +44,7 @@ class TestDateTime:
         """
         round_trip(inp, exp)
 
-    def test_long_fraction(self):
+    def test_long_fraction(self) -> None:
         inp = """
         - 2011-10-02 16:45:00.1234      # expand with zeros
         - 2011-10-02 16:45:00.123456
@@ -61,7 +61,7 @@ class TestDateTime:
         """
         round_trip(inp, exp)
 
-    def test_canonical(self):
+    def test_canonical(self) -> None:
         inp = """
         - 2011-10-02T16:45:00.1Z
         """
@@ -70,7 +70,7 @@ class TestDateTime:
         """
         round_trip(inp, exp)
 
-    def test_spaced_timezone(self):
+    def test_spaced_timezone(self) -> None:
         inp = """
         - 2011-10-02T11:45:00 -5
         """
@@ -79,7 +79,7 @@ class TestDateTime:
         """
         round_trip(inp, exp)
 
-    def test_normal_timezone(self):
+    def test_normal_timezone(self) -> None:
         round_trip("""
         - 2011-10-02T11:45:00-5
         - 2011-10-02 11:45:00-5
@@ -87,7 +87,7 @@ class TestDateTime:
         - 2011-10-02 11:45:00-05:00
         """)
 
-    def test_no_timezone(self):
+    def test_no_timezone(self) -> None:
         inp = """
         - 2011-10-02 6:45:00
         """
@@ -96,7 +96,7 @@ class TestDateTime:
         """
         round_trip(inp, exp)
 
-    def test_explicit_T(self):
+    def test_explicit_T(self) -> None:
         inp = """
         - 2011-10-02T16:45:00
         """
@@ -105,7 +105,7 @@ class TestDateTime:
         """
         round_trip(inp, exp)
 
-    def test_explicit_t(self):  # to upper
+    def test_explicit_t(self) -> None:  # to upper
         inp = """
         - 2011-10-02t16:45:00
         """
@@ -114,7 +114,7 @@ class TestDateTime:
         """
         round_trip(inp, exp)
 
-    def test_no_T_multi_space(self):
+    def test_no_T_multi_space(self) -> None:
         inp = """
         - 2011-10-02   16:45:00
         """
@@ -123,22 +123,22 @@ class TestDateTime:
         """
         round_trip(inp, exp)
 
-    def test_iso(self):
+    def test_iso(self) -> None:
         round_trip("""
         - 2011-10-02T15:45:00+01:00
         """)
 
-    def test_zero_tz(self):
+    def test_zero_tz(self) -> None:
         round_trip("""
         - 2011-10-02T15:45:00+0
         """)
 
-    def test_issue_45(self):
+    def test_issue_45(self) -> None:
         round_trip("""
         dt: 2016-08-19T22:45:47Z
         """)
 
-    def test_deepcopy_datestring(self):
+    def test_deepcopy_datestring(self) -> None:
         # reported by Quuxplusone, http://stackoverflow.com/a/41577841/1307905
         x = dedent("""\
         foo: 2016-10-12T12:34:56
@@ -146,7 +146,7 @@ class TestDateTime:
         data = copy.deepcopy(round_trip_load(x))
         assert round_trip_dump(data) == x
 
-    def test_fraction_overflow(self):
+    def test_fraction_overflow(self) -> None:
         # reported (indirectly) by Luís Ferreira
         # https://sourceforge.net/p/ruamel-yaml/tickets/414/
         inp = dedent("""\
diff --git a/_test/test_deprecation.py b/_test/test_deprecation.py
index b267e66..390c26c 100644
--- a/_test/test_deprecation.py
+++ b/_test/test_deprecation.py
@@ -1,11 +1,11 @@
 # coding: utf-8
 
 import sys
-import pytest  # NOQA
+import pytest  # type:ignore  # NOQA
 
 
-@pytest.mark.skipif(sys.version_info < (3, 7) or sys.version_info >= (3, 9),
+@pytest.mark.skipif(sys.version_info < (3, 7) or sys.version_info >= (3, 9),  # type: ignore
                     reason='collections not available?')
-def test_collections_deprecation():
+def test_collections_deprecation() -> None:
     with pytest.warns(DeprecationWarning):
-        from collections import Hashable  # NOQA
+        from collections import Hashable  # type: ignore  # NOQA
diff --git a/_test/test_documents.py b/_test/test_documents.py
index 5119f06..7c6e2e6 100644
--- a/_test/test_documents.py
+++ b/_test/test_documents.py
@@ -1,12 +1,12 @@
 # coding: utf-8
 
-import pytest  # NOQA
+import pytest  # type: ignore  # NOQA
 
 from roundtrip import round_trip, round_trip_load_all, round_trip_dump_all
 
 
 class TestDocument:
-    def test_single_doc_begin_end(self):
+    def test_single_doc_begin_end(self) -> None:
         inp = """\
         ---
         - a
@@ -15,7 +15,7 @@ class TestDocument:
         """
         round_trip(inp, explicit_start=True, explicit_end=True)
 
-    def test_multi_doc_begin_end(self):
+    def test_multi_doc_begin_end(self) -> None:
         inp = """\
         ---
         - a
@@ -29,7 +29,7 @@ class TestDocument:
         out = round_trip_dump_all(docs, explicit_start=True, explicit_end=True)
         assert out == '---\n- a\n...\n---\n- b\n...\n'
 
-    def test_multi_doc_no_start(self):
+    def test_multi_doc_no_start(self) -> None:
         inp = """\
         - a
         ...
@@ -40,7 +40,7 @@ class TestDocument:
         docs = list(round_trip_load_all(inp))
         assert docs == [['a'], ['b']]
 
-    def test_multi_doc_no_end(self):
+    def test_multi_doc_no_end(self) -> None:
         inp = """\
         - a
         ---
@@ -49,7 +49,7 @@ class TestDocument:
         docs = list(round_trip_load_all(inp))
         assert docs == [['a'], ['b']]
 
-    def test_multi_doc_ends_only(self):
+    def test_multi_doc_ends_only(self) -> None:
         # this is ok in 1.2
         inp = """\
         - a
@@ -60,7 +60,7 @@ class TestDocument:
         docs = list(round_trip_load_all(inp, version=(1, 2)))
         assert docs == [['a'], ['b']]
 
-    def test_multi_doc_ends_only_1_1(self):
+    def test_multi_doc_ends_only_1_1(self) -> None:
         from ruamel import yaml
 
         # this is not ok in 1.1
diff --git a/_test/test_fail.py b/_test/test_fail.py
index 2f90112..7fbbd07 100644
--- a/_test/test_fail.py
+++ b/_test/test_fail.py
@@ -6,14 +6,14 @@
 # on fix of ruamel.yaml, move the marked test to the appropriate test (without mark)
 # and remove remove the xyz_no_fail
 
-import pytest
+import pytest  # type: ignore
 
 from roundtrip import round_trip, dedent, round_trip_load, round_trip_dump
 
 
 class TestCommentFailures:
-    @pytest.mark.xfail(strict=True)
-    def test_set_comment_before_tag(self):
+    @pytest.mark.xfail(strict=True)  # type: ignore
+    def test_set_comment_before_tag(self) -> None:
         # no comments before tags
         round_trip("""
         # the beginning
@@ -26,7 +26,7 @@ class TestCommentFailures:
         # this is the end
         """)
 
-    def test_set_comment_before_tag_no_fail(self):
+    def test_set_comment_before_tag_no_fail(self) -> None:
         # no comments before tags
         inp = """
         # the beginning
@@ -48,15 +48,15 @@ class TestCommentFailures:
         # this is the end
         """)
 
-    @pytest.mark.xfail(strict=True)
-    def test_comment_dash_line(self):
+    @pytest.mark.xfail(strict=True)  # type: ignore
+    def test_comment_dash_line(self) -> None:
         round_trip("""
         - # abc
            a: 1
            b: 2
         """)
 
-    def test_comment_dash_line_fail(self):
+    def test_comment_dash_line_fail(self) -> None:
         x = """
         - # abc
            a: 1
@@ -72,8 +72,8 @@ class TestCommentFailures:
 
 
 class TestIndentFailures:
-    @pytest.mark.xfail(strict=True)
-    def test_indent_not_retained(self):
+    @pytest.mark.xfail(strict=True)  # type: ignore
+    def test_indent_not_retained(self) -> None:
         round_trip("""
         verbosity: 1                  # 0 is minimal output, -1 none
         base_url: http://gopher.net
@@ -97,7 +97,7 @@ class TestIndentFailures:
             -   too cold
         """)
 
-    def test_indent_not_retained_no_fail(self):
+    def test_indent_not_retained_no_fail(self) -> None:
         inp = """
         verbosity: 1                  # 0 is minimal output, -1 none
         base_url: http://gopher.net
@@ -143,7 +143,7 @@ class TestIndentFailures:
             -   too cold
         """)
 
-    def Xtest_indent_top_level_no_fail(self):
+    def Xtest_indent_top_level_no_fail(self) -> None:
         inp = """
         -   a:
             - b
@@ -152,8 +152,8 @@ class TestIndentFailures:
 
 
 class TestTagFailures:
-    @pytest.mark.xfail(strict=True)
-    def test_standard_short_tag(self):
+    @pytest.mark.xfail(strict=True)  # type: ignore
+    def test_standard_short_tag(self) -> None:
         round_trip("""\
         !!map
         name: Anthon
@@ -161,7 +161,7 @@ class TestTagFailures:
         language: python
         """)
 
-    def test_standard_short_tag_no_fail(self):
+    def test_standard_short_tag_no_fail(self) -> None:
         inp = """
         !!map
         name: Anthon
@@ -177,13 +177,13 @@ class TestTagFailures:
 
 
 class TestFlowValues:
-    def test_flow_value_with_colon(self):
+    def test_flow_value_with_colon(self) -> None:
         inp = """\
         {a: bcd:efg}
         """
         round_trip(inp)
 
-    def test_flow_value_with_colon_quoted(self):
+    def test_flow_value_with_colon_quoted(self) -> None:
         inp = """\
         {a: 'bcd:efg'}
         """
@@ -191,13 +191,13 @@ class TestFlowValues:
 
 
 class TestMappingKey:
-    def test_simple_mapping_key(self):
+    def test_simple_mapping_key(self) -> None:
         inp = """\
         {a: 1, b: 2}: hello world
         """
         round_trip(inp, preserve_quotes=True, dump_data=False)
 
-    def test_set_simple_mapping_key(self):
+    def test_set_simple_mapping_key(self) -> None:
         from ruamel.yaml.comments import CommentedKeyMap
 
         d = {CommentedKeyMap([('a', 1), ('b', 2)]): 'hello world'}
@@ -206,7 +206,7 @@ class TestMappingKey:
         """)
         assert round_trip_dump(d) == exp
 
-    def test_change_key_simple_mapping_key(self):
+    def test_change_key_simple_mapping_key(self) -> None:
         from ruamel.yaml.comments import CommentedKeyMap
 
         inp = """\
@@ -219,7 +219,7 @@ class TestMappingKey:
         """)
         assert round_trip_dump(d) == exp
 
-    def test_change_value_simple_mapping_key(self):
+    def test_change_value_simple_mapping_key(self) -> None:
         from ruamel.yaml.comments import CommentedKeyMap
 
         inp = """\
diff --git a/_test/test_float.py b/_test/test_float.py
index 8257208..582ccf0 100644
--- a/_test/test_float.py
+++ b/_test/test_float.py
@@ -1,6 +1,6 @@
 # coding: utf-8
 
-import pytest  # NOQA
+import pytest  # type: ignore  # NOQA
 
 from roundtrip import round_trip, dedent, round_trip_load, round_trip_dump  # NOQA
 
@@ -8,7 +8,7 @@ from roundtrip import round_trip, dedent, round_trip_load, round_trip_dump  # NO
 
 
 class TestFloat:
-    def test_round_trip_non_exp(self):
+    def test_round_trip_non_exp(self) -> None:
         data = round_trip("""\
         - 1.0
         - 1.00
@@ -22,6 +22,8 @@ class TestFloat:
         - .5
         - +.5
         - -.5
+        - !!float '42'
+        - !!float '-42'
         """)
         print(data)
         assert 0.999 < data[0] < 1.001
@@ -36,8 +38,10 @@ class TestFloat:
         assert .49 < data[9] < .51
         assert .49 < data[10] < .51
         assert -.51 < data[11] < -.49
+        assert 41.99 < data[12] < 42.01
+        assert 41.99 < -data[13] < 42.01
 
-    def test_round_trip_zeros_0(self):
+    def test_round_trip_zeros_0(self) -> None:
         data = round_trip("""\
         - 0.
         - +0.
@@ -53,12 +57,13 @@ class TestFloat:
         for d in data:
             assert -0.00001 < d < 0.00001
 
-    def Xtest_round_trip_non_exp_trailing_dot(self):
+    def test_round_trip_exp_trailing_dot(self) -> None:
         data = round_trip("""\
+        - 3.e4
         """)
         print(data)
 
-    def test_yaml_1_1_no_dot(self):
+    def test_yaml_1_1_no_dot(self) -> None:
         from ruamel.yaml.error import MantissaNoDotYAML1_1Warning
 
         with pytest.warns(MantissaNoDotYAML1_1Warning):
@@ -69,8 +74,8 @@ class TestFloat:
             """)
 
 
-class TestCalculations(object):
-    def test_mul_00(self):
+class TestCalculations:
+    def test_mul_00(self) -> None:
         # issue 149 reported by jan.brezina@tul.cz
         d = round_trip_load("""\
         - 0.1
diff --git a/_test/test_flowsequencekey.py b/_test/test_flowsequencekey.py
index 96bee67..be70699 100644
--- a/_test/test_flowsequencekey.py
+++ b/_test/test_flowsequencekey.py
@@ -11,7 +11,7 @@ from roundtrip import round_trip  # , dedent, round_trip_load, round_trip_dump
 
 
 class TestFlowStyleSequenceKey:
-    def test_so_39595807(self):
+    def test_so_39595807(self) -> None:
         inp = """\
         %YAML 1.2
         ---
diff --git a/_test/test_indentation.py b/_test/test_indentation.py
index 6e0fce2..1f16cb2 100644
--- a/_test/test_indentation.py
+++ b/_test/test_indentation.py
@@ -1,23 +1,24 @@
 # coding: utf-8
 
-import pytest  # NOQA
+from typing import Any
+import pytest  # type: ignore  # NOQA
 
 from roundtrip import round_trip, round_trip_load, round_trip_dump, dedent, YAML
 
 
-def rt(s):
-
+def rt(s: str) -> str:
     res = round_trip_dump(round_trip_load(s))
+    assert res is not None
     return res.strip() + '\n'
 
 
 class TestIndent:
-    def test_roundtrip_inline_list(self):
+    def test_roundtrip_inline_list(self) -> None:
         s = 'a: [a, b, c]\n'
         output = rt(s)
         assert s == output
 
-    def test_roundtrip_mapping_of_inline_lists(self):
+    def test_roundtrip_mapping_of_inline_lists(self) -> None:
         s = dedent("""\
         a: [a, b, c]
         j: [k, l, m]
@@ -25,7 +26,7 @@ class TestIndent:
         output = rt(s)
         assert s == output
 
-    def test_roundtrip_mapping_of_inline_lists_comments(self):
+    def test_roundtrip_mapping_of_inline_lists_comments(self) -> None:
         s = dedent("""\
         # comment A
         a: [a, b, c]
@@ -35,7 +36,7 @@ class TestIndent:
         output = rt(s)
         assert s == output
 
-    def test_roundtrip_mapping_of_inline_sequence_eol_comments(self):
+    def test_roundtrip_mapping_of_inline_sequence_eol_comments(self) -> None:
         s = dedent("""\
         # comment A
         a: [a, b, c]  # comment B
@@ -45,7 +46,7 @@ class TestIndent:
         assert s == output
 
     # first test by explicitly setting flow style
-    def test_added_inline_list(self):
+    def test_added_inline_list(self) -> None:
         s1 = dedent("""
         a:
         - b
@@ -62,7 +63,7 @@ class TestIndent:
 
     # ############ flow mappings
 
-    def test_roundtrip_flow_mapping(self):
+    def test_roundtrip_flow_mapping(self) -> None:
         s = dedent("""\
         - {a: 1, b: hallo}
         - {j: fka, k: 42}
@@ -71,7 +72,7 @@ class TestIndent:
         output = round_trip_dump(data)
         assert s == output
 
-    def test_roundtrip_sequence_of_inline_mappings_eol_comments(self):
+    def test_roundtrip_sequence_of_inline_mappings_eol_comments(self) -> None:
         s = dedent("""\
         # comment A
         - {a: 1, b: hallo}  # comment B
@@ -80,14 +81,14 @@ class TestIndent:
         output = rt(s)
         assert s == output
 
-    def test_indent_top_level(self):
+    def test_indent_top_level(self) -> None:
         inp = """
         -   a:
             -   b
         """
         round_trip(inp, indent=4)
 
-    def test_set_indent_5_block_list_indent_1(self):
+    def test_set_indent_5_block_list_indent_1(self) -> None:
         inp = """
         a:
          -   b: c
@@ -97,7 +98,7 @@ class TestIndent:
         """
         round_trip(inp, indent=5, block_seq_indent=1)
 
-    def test_set_indent_4_block_list_indent_2(self):
+    def test_set_indent_4_block_list_indent_2(self) -> None:
         inp = """
         a:
           - b: c
@@ -107,7 +108,7 @@ class TestIndent:
         """
         round_trip(inp, indent=4, block_seq_indent=2)
 
-    def test_set_indent_3_block_list_indent_0(self):
+    def test_set_indent_3_block_list_indent_0(self) -> None:
         inp = """
         a:
         -  b: c
@@ -117,7 +118,7 @@ class TestIndent:
         """
         round_trip(inp, indent=3, block_seq_indent=0)
 
-    def Xtest_set_indent_3_block_list_indent_2(self):
+    def Xtest_set_indent_3_block_list_indent_2(self) -> None:
         inp = """
         a:
           -
@@ -131,7 +132,7 @@ class TestIndent:
         """
         round_trip(inp, indent=3, block_seq_indent=2)
 
-    def test_set_indent_3_block_list_indent_2(self):
+    def test_set_indent_3_block_list_indent_2(self) -> None:
         inp = """
         a:
           - b: c
@@ -141,7 +142,7 @@ class TestIndent:
         """
         round_trip(inp, indent=3, block_seq_indent=2)
 
-    def Xtest_set_indent_2_block_list_indent_2(self):
+    def Xtest_set_indent_2_block_list_indent_2(self) -> None:
         inp = """
         a:
           -
@@ -156,7 +157,7 @@ class TestIndent:
         round_trip(inp, indent=2, block_seq_indent=2)
 
     # this is how it should be: block_seq_indent stretches the indent
-    def test_set_indent_2_block_list_indent_2(self):
+    def test_set_indent_2_block_list_indent_2(self) -> None:
         inp = """
         a:
           - b: c
@@ -167,7 +168,7 @@ class TestIndent:
         round_trip(inp, indent=2, block_seq_indent=2)
 
     # have to set indent!
-    def test_roundtrip_four_space_indents(self):
+    def test_roundtrip_four_space_indents(self) -> None:
         # fmt: off
         s = (
             'a:\n'
@@ -177,7 +178,7 @@ class TestIndent:
         # fmt: on
         round_trip(s, indent=4)
 
-    def test_roundtrip_four_space_indents_no_fail(self):
+    def test_roundtrip_four_space_indents_no_fail(self) -> None:
         inp = """
         a:
         -   foo
@@ -192,7 +193,7 @@ class TestIndent:
 
 
 class TestYpkgIndent:
-    def test_00(self):
+    def test_00(self) -> None:
         inp = """
         name       : nano
         version    : 2.3.2
@@ -214,7 +215,7 @@ class TestYpkgIndent:
         )
 
 
-def guess(s):
+def guess(s: str) -> Any:
     from ruamel.yaml.util import load_yaml_guess_indent
 
     x, y, z = load_yaml_guess_indent(dedent(s))
@@ -222,21 +223,21 @@ def guess(s):
 
 
 class TestGuessIndent:
-    def test_guess_20(self):
+    def test_guess_20(self) -> None:
         inp = """\
         a:
         - 1
         """
         assert guess(inp) == (2, 0)
 
-    def test_guess_42(self):
+    def test_guess_42(self) -> None:
         inp = """\
         a:
           - 1
         """
         assert guess(inp) == (4, 2)
 
-    def test_guess_42a(self):
+    def test_guess_42a(self) -> None:
         # block seq indent prevails over nested key indent level
         inp = """\
         b:
@@ -245,7 +246,7 @@ class TestGuessIndent:
         """
         assert guess(inp) == (4, 2)
 
-    def test_guess_3None(self):
+    def test_guess_3None(self) -> None:
         inp = """\
         b:
            a: 1
@@ -256,7 +257,7 @@ class TestGuessIndent:
 class TestSeparateMapSeqIndents:
     # using uncommon 6 indent with 3 push in as 2 push in automatically
     # gets you 4 indent even if not set
-    def test_00(self):
+    def test_00(self) -> None:
         # old style
         yaml = YAML()
         yaml.indent = 6
@@ -268,7 +269,7 @@ class TestSeparateMapSeqIndents:
         """
         yaml.round_trip(inp)
 
-    def test_01(self):
+    def test_01(self) -> None:
         yaml = YAML()
         yaml.indent(sequence=6)
         yaml.indent(offset=3)
@@ -279,7 +280,7 @@ class TestSeparateMapSeqIndents:
         """
         yaml.round_trip(inp)
 
-    def test_02(self):
+    def test_02(self) -> None:
         yaml = YAML()
         yaml.indent(mapping=5, sequence=6, offset=3)
         inp = """
@@ -290,7 +291,7 @@ class TestSeparateMapSeqIndents:
         """
         yaml.round_trip(inp)
 
-    def test_03(self):
+    def test_03(self) -> None:
         inp = """
         a:
             b:
@@ -300,7 +301,7 @@ class TestSeparateMapSeqIndents:
         """
         round_trip(inp, indent=4)
 
-    def test_04(self):
+    def test_04(self) -> None:
         yaml = YAML()
         yaml.indent(mapping=5, sequence=6)
         inp = """
@@ -312,7 +313,7 @@ class TestSeparateMapSeqIndents:
         """
         yaml.round_trip(inp)
 
-    def test_issue_51(self):
+    def test_issue_51(self) -> None:
         yaml = YAML()
         # yaml.map_indent = 2 # the default
         yaml.indent(sequence=4, offset=2)
diff --git a/_test/test_int.py b/_test/test_int.py
index aa300df..92fb92a 100644
--- a/_test/test_int.py
+++ b/_test/test_int.py
@@ -1,6 +1,6 @@
 # coding: utf-8
 
-import pytest  # NOQA
+import pytest  # type: ignore  # NOQA
 
 from roundtrip import dedent, round_trip_load, round_trip_dump
 
@@ -8,7 +8,7 @@ from roundtrip import dedent, round_trip_load, round_trip_dump
 
 
 class TestBinHexOct:
-    def test_calculate(self):
+    def test_calculate(self) -> None:
         # make sure type, leading zero(s) and underscore are preserved
         s = dedent("""\
         - 42
diff --git a/_test/test_issues.py b/_test/test_issues.py
index 736dccb..7106453 100644
--- a/_test/test_issues.py
+++ b/_test/test_issues.py
@@ -1,6 +1,8 @@
 # coding: utf-8
 
-import pytest  # NOQA
+from typing import Any
+
+import pytest  # type: ignore  # NOQA
 
 
 from roundtrip import (
@@ -15,7 +17,7 @@ from roundtrip import (
 
 
 class TestIssues:
-    def test_issue_61(self):
+    def test_issue_61(self) -> None:
         s = dedent("""
         def1: &ANCHOR1
             key1: value1
@@ -29,54 +31,54 @@ class TestIssues:
         assert str(data['comb']) == str(data['def'])
         assert str(data['comb']) == "ordereddict([('key', 'value'), ('key1', 'value1')])"
 
-    def test_issue_82(self, tmpdir):
-        program_src = r'''
-        from ruamel import yaml
-        import re
-
-        class SINumber(yaml.YAMLObject):
-            PREFIXES = {'k': 1e3, 'M': 1e6, 'G': 1e9}
-            yaml_loader = yaml.Loader
-            yaml_dumper = yaml.Dumper
-            yaml_tag = '!si'
-            yaml_implicit_pattern = re.compile(
-                r'^(?P<value>[0-9]+(?:\.[0-9]+)?)(?P<prefix>[kMG])$')
-
-            @classmethod
-            def from_yaml(cls, loader, node):
-                return cls(node.value)
-
-            @classmethod
-            def to_yaml(cls, dumper, data):
-                return dumper.represent_scalar(cls.yaml_tag, str(data))
-
-            def __init__(self, *args):
-                m = self.yaml_implicit_pattern.match(args[0])
-                self.value = float(m.groupdict()['value'])
-                self.prefix = m.groupdict()['prefix']
-
-            def __str__(self):
-                return str(self.value)+self.prefix
-
-            def __int__(self):
-                return int(self.value*self.PREFIXES[self.prefix])
-
-        # This fails:
-        yaml.add_implicit_resolver(SINumber.yaml_tag, SINumber.yaml_implicit_pattern)
-
-        ret = yaml.load("""
-        [1,2,3, !si 10k, 100G]
-        """, Loader=yaml.Loader)
-        for idx, l in enumerate([1, 2, 3, 10000, 100000000000]):
-            assert int(ret[idx]) == l
-        '''
-        assert save_and_run(dedent(program_src), tmpdir) == 0
-
-    def test_issue_82rt(self, tmpdir):
+#    def test_issue_82(self, tmpdir):
+#        program_src = r'''
+#        from ruamel import yaml
+#        import re
+#
+#        class SINumber(yaml.YAMLObject):
+#            PREFIXES = {'k': 1e3, 'M': 1e6, 'G': 1e9}
+#            yaml_loader = yaml.Loader
+#            yaml_dumper = yaml.Dumper
+#            yaml_tag = '!si'
+#            yaml_implicit_pattern = re.compile(
+#                r'^(?P<value>[0-9]+(?:\.[0-9]+)?)(?P<prefix>[kMG])$')
+#
+#            @classmethod
+#            def from_yaml(cls, loader, node):
+#                return cls(node.value)
+#
+#            @classmethod
+#            def to_yaml(cls, dumper, data):
+#                return dumper.represent_scalar(cls.yaml_tag, str(data))
+#
+#            def __init__(self, *args):
+#                m = self.yaml_implicit_pattern.match(args[0])
+#                self.value = float(m.groupdict()['value'])
+#                self.prefix = m.groupdict()['prefix']
+#
+#            def __str__(self) -> None:
+#                return str(self.value)+self.prefix
+#
+#            def __int__(self) -> None:
+#                return int(self.value*self.PREFIXES[self.prefix])
+#
+#        # This fails:
+#        yaml.add_implicit_resolver(SINumber.yaml_tag, SINumber.yaml_implicit_pattern)
+#
+#        ret = yaml.load("""
+#        [1,2,3, !si 10k, 100G]
+#        """, Loader=yaml.Loader)
+#        for idx, l in enumerate([1, 2, 3, 10000, 100000000000]):
+#            assert int(ret[idx]) == l
+#        '''
+#        assert save_and_run(dedent(program_src), tmpdir) == 0
+
+    def test_issue_82rt(self, tmpdir: Any) -> None:
         yaml_str = '[1, 2, 3, !si 10k, 100G]\n'
         x = round_trip(yaml_str, preserve_quotes=True)  # NOQA
 
-    def test_issue_102(self):
+    def test_issue_102(self) -> None:
         yaml_str = dedent("""
         var1: #empty
         var2: something #notempty
@@ -86,8 +88,8 @@ class TestIssues:
         """)
         x = round_trip(yaml_str, preserve_quotes=True)  # NOQA
 
-    def test_issue_150(self):
-        from ruamel.yaml import YAML
+    def test_issue_150(self) -> None:
+        from ruamel.yaml import YAML  # type: ignore
 
         inp = """\
         base: &base_key
@@ -103,7 +105,7 @@ class TestIssues:
         child = data['child']
         assert 'second' in dict(**child)
 
-    def test_issue_160(self):
+    def test_issue_160(self) -> None:
         from ruamel.yaml.compat import StringIO
         s = dedent("""\
         root:
@@ -127,7 +129,7 @@ class TestIssues:
         """)
         assert buf.getvalue() == exp
 
-    def test_issue_161(self):
+    def test_issue_161(self) -> None:
         yaml_str = dedent("""\
         mapping-A:
           key-A:{}
@@ -137,7 +139,7 @@ class TestIssues:
             s = yaml_str.format(comment)
             res = round_trip(s)  # NOQA
 
-    def test_issue_161a(self):
+    def test_issue_161a(self) -> None:
         yaml_str = dedent("""\
         mapping-A:
           key-A:{}
@@ -147,7 +149,7 @@ class TestIssues:
             s = yaml_str.format(comment)
             res = round_trip(s)  # NOQA
 
-    def test_issue_163(self):
+    def test_issue_163(self) -> None:
         s = dedent("""\
         some-list:
         # List comment
@@ -163,19 +165,19 @@ class TestIssues:
 
     json_str2 = '{"abc":[{"a":"1", "uses":0}]}'
 
-    def test_issue_172(self):
+    def test_issue_172(self) -> None:
         x = round_trip_load(TestIssues.json_str2)  # NOQA
         x = round_trip_load(TestIssues.json_str)  # NOQA
 
-    def test_issue_176(self):
+    def test_issue_176(self) -> None:
         # basic request by Stuart Berg
-        from ruamel.yaml import YAML
+        from ruamel.yaml import YAML  # type: ignore
 
         yaml = YAML()
         seq = yaml.load('[1,2,3]')
         seq[:] = [1, 2, 3, 4]
 
-    def test_issue_176_preserve_comments_on_extended_slice_assignment(self):
+    def test_issue_176_preserve_comments_on_extended_slice_assignment(self) -> None:
         yaml_str = dedent("""\
         - a
         - b  # comment
@@ -190,7 +192,7 @@ class TestIssues:
         res = round_trip_dump(seq)
         assert res == yaml_str.replace(' b ', ' B ').replace(' d\n', ' D\n')
 
-    def test_issue_176_test_slicing(self):
+    def test_issue_176_test_slicing(self) -> None:
         mss = round_trip_load('[0, 1, 2, 3, 4]')
         assert len(mss) == 5
         assert mss[2:2] == []
@@ -240,7 +242,7 @@ class TestIssues:
         del m[:]
         assert m == []
 
-    def test_issue_184(self):
+    def test_issue_184(self) -> None:
         yaml_str = dedent("""\
         test::test:
           # test
@@ -252,20 +254,20 @@ class TestIssues:
         d.yaml_add_eol_comment('test1', 'bar')
         assert round_trip_dump(d) == yaml_str + 'bar: foo # test1\n'
 
-    def test_issue_219(self):
+    def test_issue_219(self) -> None:
         yaml_str = dedent("""\
         [StackName: AWS::StackName]
         """)
         d = round_trip_load(yaml_str)  # NOQA
 
-    def test_issue_219a(self):
+    def test_issue_219a(self) -> None:
         yaml_str = dedent("""\
         [StackName:
         AWS::StackName]
         """)
         d = round_trip_load(yaml_str)  # NOQA
 
-    def test_issue_220(self, tmpdir):
+    def test_issue_220(self, tmpdir: Any) -> None:
         program_src = r'''
         from ruamel.yaml import YAML
 
@@ -280,14 +282,14 @@ class TestIssues:
         '''
         assert save_and_run(dedent(program_src), tmpdir, optimized=True) == 0
 
-    def test_issue_221_add(self):
+    def test_issue_221_add(self) -> None:
         from ruamel.yaml.comments import CommentedSeq
 
         a = CommentedSeq([1, 2, 3])
         a + [4, 5]
 
-    def test_issue_221_sort(self):
-        from ruamel.yaml import YAML
+    def test_issue_221_sort(self) -> None:
+        from ruamel.yaml import YAML  # type: ignore
         from ruamel.yaml.compat import StringIO
 
         yaml = YAML()
@@ -311,8 +313,8 @@ class TestIssues:
         """)
         assert buf.getvalue() == exp
 
-    def test_issue_221_sort_reverse(self):
-        from ruamel.yaml import YAML
+    def test_issue_221_sort_reverse(self) -> None:
+        from ruamel.yaml import YAML  # type: ignore
         from ruamel.yaml.compat import StringIO
 
         yaml = YAML()
@@ -336,8 +338,8 @@ class TestIssues:
         """)
         assert buf.getvalue() == exp
 
-    def test_issue_221_sort_key(self):
-        from ruamel.yaml import YAML
+    def test_issue_221_sort_key(self) -> None:
+        from ruamel.yaml import YAML  # type: ignore
         from ruamel.yaml.compat import StringIO
 
         yaml = YAML()
@@ -361,8 +363,8 @@ class TestIssues:
         """)
         assert buf.getvalue() == exp
 
-    def test_issue_221_sort_key_reverse(self):
-        from ruamel.yaml import YAML
+    def test_issue_221_sort_key_reverse(self) -> None:
+        from ruamel.yaml import YAML  # type: ignore
         from ruamel.yaml.compat import StringIO
 
         yaml = YAML()
@@ -386,7 +388,7 @@ class TestIssues:
         """)
         assert buf.getvalue() == exp
 
-    def test_issue_222(self):
+    def test_issue_222(self) -> None:
         import ruamel.yaml
         from ruamel.yaml.compat import StringIO
 
@@ -395,13 +397,13 @@ class TestIssues:
         yaml.dump(['012923'], buf)
         assert buf.getvalue() == "['012923']\n"
 
-    def test_issue_223(self):
+    def test_issue_223(self) -> None:
         import ruamel.yaml
 
         yaml = ruamel.yaml.YAML(typ='safe')
         yaml.load('phone: 0123456789')
 
-    def test_issue_232(self):
+    def test_issue_232(self) -> None:
         import ruamel.yaml
 
         yaml = YAML(typ='safe', pure=True)
@@ -411,24 +413,24 @@ class TestIssues:
         with pytest.raises(ruamel.yaml.parser.ParserError):
             yaml.load('{]')
 
-    def test_issue_233(self):
-        from ruamel.yaml import YAML
+    def test_issue_233(self) -> None:
+        from ruamel.yaml import YAML  # type: ignore
         import json
 
         yaml = YAML()
         data = yaml.load('{}')
         json_str = json.dumps(data)  # NOQA
 
-    def test_issue_233a(self):
-        from ruamel.yaml import YAML
+    def test_issue_233a(self) -> None:
+        from ruamel.yaml import YAML  # type: ignore
         import json
 
         yaml = YAML()
         data = yaml.load('[]')
         json_str = json.dumps(data)  # NOQA
 
-    def test_issue_234(self):
-        from ruamel.yaml import YAML
+    def test_issue_234(self) -> None:
+        from ruamel.yaml import YAML  # type: ignore
 
         inp = dedent("""\
         - key: key1
@@ -444,7 +446,7 @@ class TestIssues:
         print(repr(fold))
         assert '\a' not in fold
 
-    def test_issue_236(self):
+    def test_issue_236(self) -> None:
         inp = """
         conf:
           xx: {a: "b", c: []}
@@ -452,7 +454,7 @@ class TestIssues:
         """
         d = round_trip(inp, preserve_quotes=True)  # NOQA
 
-    def test_issue_238(self, tmpdir):
+    def test_issue_238(self, tmpdir: Any) -> None:
         program_src = r"""
         import ruamel.yaml
         from ruamel.yaml.compat import StringIO
@@ -484,7 +486,7 @@ class TestIssues:
         """
         assert save_and_run(dedent(program_src), tmpdir) == 0
 
-    def test_issue_239(self):
+    def test_issue_239(self) -> None:
         inp = """
         first_name: Art
         occupation: Architect
@@ -504,14 +506,14 @@ class TestIssues:
         """
         d = YAML().round_trip_all(inp)  # NOQA
 
-    def test_issue_242(self):
+    def test_issue_242(self) -> None:
         from ruamel.yaml.comments import CommentedMap
 
         d0 = CommentedMap([('a', 'b')])
         assert d0['a'] == 'b'
 
-    def test_issue_245(self):
-        from ruamel.yaml import YAML
+    def test_issue_245(self) -> None:
+        from ruamel.yaml import YAML  # type: ignore
         inp = """
         d: yes
         """
@@ -528,7 +530,7 @@ class TestIssues:
             print(typ, yaml.parser, yaml.resolver)
             assert d['d'] is True
 
-    def test_issue_249(self):
+    def test_issue_249(self) -> None:
         yaml = YAML()
         inp = dedent("""\
         # comment
@@ -545,7 +547,7 @@ class TestIssues:
         """)
         yaml.round_trip(inp, outp=exp)  # NOQA
 
-    def test_issue_250(self):
+    def test_issue_250(self) -> None:
         inp = """
         # 1.
         - - 1
@@ -557,8 +559,8 @@ class TestIssues:
         d = round_trip(inp)  # NOQA
 
     # @pytest.mark.xfail(strict=True, reason='bla bla', raises=AssertionError)
-    def test_issue_279(self):
-        from ruamel.yaml import YAML
+    def test_issue_279(self) -> None:
+        from ruamel.yaml import YAML  # type: ignore
         from ruamel.yaml.compat import StringIO
 
         yaml = YAML()
@@ -576,8 +578,8 @@ class TestIssues:
         print(buf.getvalue())
         assert buf.getvalue() == inp
 
-    def test_issue_280(self):
-        from ruamel.yaml import YAML
+    def test_issue_280(self) -> None:
+        from ruamel.yaml import YAML  # type: ignore
         from ruamel.yaml.representer import RepresenterError
         from collections import namedtuple
         from sys import stdout
@@ -587,7 +589,7 @@ class TestIssues:
         with pytest.raises(RepresenterError, match='cannot represent'):
             yaml.dump({'t': t}, stdout)
 
-    def test_issue_282(self):
+    def test_issue_282(self) -> None:
         # update from list of tuples caused AttributeError
         import ruamel.yaml
         yaml_data = ruamel.yaml.comments.CommentedMap([('a', 'apple'), ('b', 'banana')])
@@ -596,7 +598,7 @@ class TestIssues:
         assert 'c' in yaml_data.keys()
         assert 'c' in yaml_data._ok
 
-    def test_issue_284(self):
+    def test_issue_284(self) -> None:
         import ruamel.yaml
         inp = dedent("""\
         plain key: in-line value
@@ -614,8 +616,8 @@ class TestIssues:
         with pytest.raises(ruamel.yaml.parser.ParserError, match='expected <block end>'):
             d = yaml.load(inp)
 
-    def test_issue_285(self):
-        from ruamel.yaml import YAML
+    def test_issue_285(self) -> None:
+        from ruamel.yaml import YAML  # type: ignore
 
         yaml = YAML()
         inp = dedent("""\
@@ -632,8 +634,8 @@ class TestIssues:
         assert not a[1]
         assert not a[3]
 
-    def test_issue_286(self):
-        from ruamel.yaml import YAML
+    def test_issue_286(self) -> None:
+        from ruamel.yaml import YAML  # type: ignore
         from ruamel.yaml.compat import StringIO
 
         yaml = YAML()
@@ -648,10 +650,10 @@ class TestIssues:
         yaml.dump(a, buf)
         assert buf.getvalue().endswith('xxx\nnew_key: new_value\n')
 
-    def test_issue_288(self):
+    def test_issue_288(self) -> None:
         import sys
         from ruamel.yaml.compat import StringIO
-        from ruamel.yaml import YAML
+        from ruamel.yaml import YAML  # type: ignore
 
         yamldoc = dedent("""\
         ---
@@ -679,10 +681,10 @@ class TestIssues:
         yaml.dump(data, buf)
         assert buf.getvalue() == yamldoc
 
-    def test_issue_288a(self):
+    def test_issue_288a(self) -> None:
         import sys
         from ruamel.yaml.compat import StringIO
-        from ruamel.yaml import YAML
+        from ruamel.yaml import YAML  # type: ignore
 
         yamldoc = dedent("""\
         ---
@@ -710,10 +712,10 @@ class TestIssues:
         yaml.dump(data, buf)
         assert buf.getvalue() == yamldoc
 
-    def test_issue_290(self):
+    def test_issue_290(self) -> None:
         import sys
         from ruamel.yaml.compat import StringIO
-        from ruamel.yaml import YAML
+        from ruamel.yaml import YAML  # type: ignore
 
         yamldoc = dedent("""\
         ---
@@ -746,10 +748,10 @@ class TestIssues:
         yaml.dump(data, buf)
         assert buf.getvalue() == yamldoc
 
-    def test_issue_290a(self):
+    def test_issue_290a(self) -> None:
         import sys
         from ruamel.yaml.compat import StringIO
-        from ruamel.yaml import YAML
+        from ruamel.yaml import YAML  # type: ignore
 
         yamldoc = dedent("""\
         ---
@@ -783,7 +785,7 @@ class TestIssues:
         assert buf.getvalue() == yamldoc
 
     # @pytest.mark.xfail(strict=True, reason='should fail pre 0.15.100', raises=AssertionError)
-    def test_issue_295(self):
+    def test_issue_295(self) -> None:
         # deepcopy also makes a copy of the start and end mark, and these did not
         # have any comparison beyond their ID, which of course changed, breaking
         # some old merge_comment code
@@ -808,8 +810,8 @@ class TestIssues:
         dc = copy.deepcopy(data)
         assert round_trip_dump(dc) == inp
 
-    def test_issue_300(self):
-        from ruamel.yaml import YAML
+    def test_issue_300(self) -> None:
+        from ruamel.yaml import YAML  # type: ignore
 
         inp = dedent("""
         %YAML 1.2
@@ -819,7 +821,7 @@ class TestIssues:
         """)
         YAML().load(inp)
 
-    def test_issue_300a(self):
+    def test_issue_300a(self) -> None:
         import ruamel.yaml
 
         inp = dedent("""
@@ -833,7 +835,7 @@ class TestIssues:
                            match='while scanning a directive'):
             yaml.load(inp)
 
-    def test_issue_304(self):
+    def test_issue_304(self) -> None:
         inp = """
         %YAML 1.2
         %TAG ! tag:example.com,2019:
@@ -843,7 +845,7 @@ class TestIssues:
         """
         d = na_round_trip(inp)  # NOQA
 
-    def test_issue_305(self):
+    def test_issue_305(self) -> None:
         inp = """
         %YAML 1.2
         ---
@@ -852,7 +854,7 @@ class TestIssues:
         """
         d = na_round_trip(inp)  # NOQA
 
-    def test_issue_307(self):
+    def test_issue_307(self) -> None:
         inp = """
         %YAML 1.2
         %TAG ! tag:example.com,2019/path#
@@ -863,7 +865,7 @@ class TestIssues:
         d = na_round_trip(inp)  # NOQA
 
 #    @pytest.mark.xfail(strict=True, reason='bla bla', raises=AssertionError)
-#    def test_issue_ xxx(self):
+#    def test_issue_ xxx(self) -> None:
 #        inp = """
 #        """
 #        d = round_trip(inp)  # NOQA
diff --git a/_test/test_json_numbers.py b/_test/test_json_numbers.py
index d89453c..08f39d0 100644
--- a/_test/test_json_numbers.py
+++ b/_test/test_json_numbers.py
@@ -1,11 +1,13 @@
 # coding: utf-8
 
-import pytest  # NOQA
+import pytest  # type: ignore  # NOQA
 
 import json
 
+from typing import Any
 
-def load(s, typ=float):
+
+def load(s: str, typ: Any = float) -> float:
     import ruamel.yaml
 
     yaml = ruamel.yaml.YAML()
@@ -16,7 +18,7 @@ def load(s, typ=float):
     assert isinstance(res['low'], typ)
     ret_val = yaml.load(x)
     print(ret_val)
-    return ret_val['low']
+    return ret_val['low']  # type: ignore
 
 
 class TestJSONNumbers:
@@ -26,7 +28,7 @@ class TestJSONNumbers:
     # -? [1-9] ( \. [0-9]* [1-9] )? ( e [-+] [1-9] [0-9]* )?
     #
     # which is not a superset of the JSON numbers
-    def test_json_number_float(self):
+    def test_json_number_float(self) -> None:
         for x in (
             y.split('#')[0].strip()
             for y in """
@@ -43,7 +45,7 @@ class TestJSONNumbers:
             res = load(x)
             assert isinstance(res, float)
 
-    def test_json_number_int(self):
+    def test_json_number_int(self) -> None:
         for x in (
             y.split('#')[0].strip()
             for y in """
diff --git a/_test/test_line_col.py b/_test/test_line_col.py
index febe9c2..5ba125e 100644
--- a/_test/test_line_col.py
+++ b/_test/test_line_col.py
@@ -1,16 +1,18 @@
 # coding: utf-8
 
-import pytest  # NOQA
+import pytest  # type: ignore  # NOQA
 
 from roundtrip import round_trip, dedent, round_trip_load, round_trip_dump  # NOQA
 
+from typing import Any
 
-def load(s):
+
+def load(s: str) -> Any:
     return round_trip_load(dedent(s))
 
 
 class TestLineCol:
-    def test_item_00(self):
+    def test_item_00(self) -> None:
         data = load("""
             - a
             - e
@@ -20,7 +22,7 @@ class TestLineCol:
         assert data[2].lc.line == 2
         assert data[2].lc.col == 2
 
-    def test_item_01(self):
+    def test_item_01(self) -> None:
         data = load("""
             - a
             - e
@@ -30,7 +32,7 @@ class TestLineCol:
         assert data[2].lc.line == 2
         assert data[2].lc.col == 2
 
-    def test_item_02(self):
+    def test_item_02(self) -> None:
         data = load("""
             - a
             - e
@@ -40,7 +42,7 @@ class TestLineCol:
         assert data[2].lc.line == 2
         assert data[2].lc.col == 2
 
-    def test_item_03(self):
+    def test_item_03(self) -> None:
         data = load("""
             - a
             - e
@@ -52,7 +54,7 @@ class TestLineCol:
         assert data[2].lc.line == 2
         assert data[2].lc.col == 2
 
-    def test_item_04(self):
+    def test_item_04(self) -> None:
         data = load("""
          # testing line and column based on SO
          # http://stackoverflow.com/questions/13319067/
@@ -66,7 +68,7 @@ class TestLineCol:
         assert data[1].lc.line == 4
         assert data[1].lc.col == 2
 
-    def test_pos_mapping(self):
+    def test_pos_mapping(self) -> None:
         data = load("""
         a: 1
         b: 2
@@ -78,7 +80,7 @@ class TestLineCol:
         assert data.lc.key('klm') == (4, 0)
         assert data.lc.value('klm') == (4, 5)
 
-    def test_pos_sequence(self):
+    def test_pos_sequence(self) -> None:
         data = load("""
         - a
         - b
diff --git a/_test/test_literal.py b/_test/test_literal.py
index 7192207..0cf34bc 100644
--- a/_test/test_literal.py
+++ b/_test/test_literal.py
@@ -1,6 +1,6 @@
 # coding: utf-8
 
-import pytest  # NOQA
+import pytest  # type: ignore  # NOQA
 
 from roundtrip import YAML  # does an automatic dedent on load
 
@@ -27,7 +27,7 @@ YAML 1.2 is again clear about root literal level scalar after directive in examp
 
 
 class TestNoIndent:
-    def test_root_literal_scalar_indent_example_9_5(self):
+    def test_root_literal_scalar_indent_example_9_5(self) -> None:
         yaml = YAML()
         s = '%!PS-Adobe-2.0'
         inp = """
@@ -38,7 +38,7 @@ class TestNoIndent:
         print(d)
         assert d == s + '\n'
 
-    def test_root_literal_scalar_no_indent(self):
+    def test_root_literal_scalar_no_indent(self) -> None:
         yaml = YAML()
         s = 'testing123'
         inp = """
@@ -49,7 +49,7 @@ class TestNoIndent:
         print(d)
         assert d == s + '\n'
 
-    def test_root_literal_scalar_no_indent_1_1(self):
+    def test_root_literal_scalar_no_indent_1_1(self) -> None:
         yaml = YAML()
         s = 'testing123'
         inp = """
@@ -61,9 +61,9 @@ class TestNoIndent:
         print(d)
         assert d == s + '\n'
 
-    def test_root_literal_scalar_no_indent_1_1_old_style(self):
+    def test_root_literal_scalar_no_indent_1_1_old_style(self) -> None:
         from textwrap import dedent
-        from ruamel.yaml import YAML
+        from ruamel.yaml import YAML  # type: ignore
 
         yaml = YAML(typ='safe', pure=True)
         s = 'testing123'
@@ -76,7 +76,7 @@ class TestNoIndent:
         print(d)
         assert d == s + '\n'
 
-    def test_root_literal_scalar_no_indent_1_1_no_raise(self):
+    def test_root_literal_scalar_no_indent_1_1_no_raise(self) -> None:
         # from ruamel.yaml.parser import ParserError
 
         yaml = YAML()
@@ -91,7 +91,7 @@ class TestNoIndent:
             """
             yaml.load(inp.format(s))
 
-    def test_root_literal_scalar_indent_offset_one(self):
+    def test_root_literal_scalar_indent_offset_one(self) -> None:
         yaml = YAML()
         s = 'testing123'
         inp = """
@@ -102,7 +102,7 @@ class TestNoIndent:
         print(d)
         assert d == s + '\n'
 
-    def test_root_literal_scalar_indent_offset_four(self):
+    def test_root_literal_scalar_indent_offset_four(self) -> None:
         yaml = YAML()
         s = 'testing123'
         inp = """
@@ -113,7 +113,7 @@ class TestNoIndent:
         print(d)
         assert d == s + '\n'
 
-    def test_root_literal_scalar_indent_offset_two_leading_space(self):
+    def test_root_literal_scalar_indent_offset_two_leading_space(self) -> None:
         yaml = YAML()
         s = ' testing123'
         inp = """
@@ -125,7 +125,7 @@ class TestNoIndent:
         print(d)
         assert d == (s + '\n') * 2
 
-    def test_root_literal_scalar_no_indent_special(self):
+    def test_root_literal_scalar_no_indent_special(self) -> None:
         yaml = YAML()
         s = '%!PS-Adobe-2.0'
         inp = """
@@ -136,7 +136,7 @@ class TestNoIndent:
         print(d)
         assert d == s + '\n'
 
-    def test_root_folding_scalar_indent(self):
+    def test_root_folding_scalar_indent(self) -> None:
         yaml = YAML()
         s = '%!PS-Adobe-2.0'
         inp = """
@@ -147,7 +147,7 @@ class TestNoIndent:
         print(d)
         assert d == s + '\n'
 
-    def test_root_folding_scalar_no_indent(self):
+    def test_root_folding_scalar_no_indent(self) -> None:
         yaml = YAML()
         s = 'testing123'
         inp = """
@@ -158,7 +158,7 @@ class TestNoIndent:
         print(d)
         assert d == s + '\n'
 
-    def test_root_folding_scalar_no_indent_special(self):
+    def test_root_folding_scalar_no_indent_special(self) -> None:
         yaml = YAML()
         s = '%!PS-Adobe-2.0'
         inp = """
@@ -169,7 +169,7 @@ class TestNoIndent:
         print(d)
         assert d == s + '\n'
 
-    def test_root_literal_multi_doc(self):
+    def test_root_literal_multi_doc(self) -> None:
         yaml = YAML(typ='safe', pure=True)
         s1 = 'abc'
         s2 = 'klm'
@@ -183,7 +183,7 @@ class TestNoIndent:
             print('d1:', d1)
             assert ['abc', 'klm\n'][idx] == d1
 
-    def test_root_literal_doc_indent_directives_end(self):
+    def test_root_literal_doc_indent_directives_end(self) -> None:
         yaml = YAML()
         yaml.explicit_start = True
         inp = """
@@ -194,7 +194,7 @@ class TestNoIndent:
         """
         yaml.round_trip(inp)
 
-    def test_root_literal_doc_indent_document_end(self):
+    def test_root_literal_doc_indent_document_end(self) -> None:
         yaml = YAML()
         yaml.explicit_start = True
         inp = """
@@ -205,7 +205,7 @@ class TestNoIndent:
         """
         yaml.round_trip(inp)
 
-    def test_root_literal_doc_indent_marker(self):
+    def test_root_literal_doc_indent_marker(self) -> None:
         yaml = YAML()
         yaml.explicit_start = True
         inp = """
@@ -217,7 +217,7 @@ class TestNoIndent:
         print(type(d), repr(d))
         yaml.round_trip(inp)
 
-    def test_nested_literal_doc_indent_marker(self):
+    def test_nested_literal_doc_indent_marker(self) -> None:
         yaml = YAML()
         yaml.explicit_start = True
         inp = """
@@ -232,7 +232,7 @@ class TestNoIndent:
 
 
 class Test_RoundTripLiteral:
-    def test_rt_root_literal_scalar_no_indent(self):
+    def test_rt_root_literal_scalar_no_indent(self) -> None:
         yaml = YAML()
         yaml.explicit_start = True
         s = 'testing123'
@@ -244,7 +244,7 @@ class Test_RoundTripLiteral:
         d = yaml.load(ys)
         yaml.dump(d, compare=ys)
 
-    def test_rt_root_literal_scalar_indent(self):
+    def test_rt_root_literal_scalar_indent(self) -> None:
         yaml = YAML()
         yaml.explicit_start = True
         yaml.indent = 4
@@ -257,7 +257,7 @@ class Test_RoundTripLiteral:
         d = yaml.load(ys)
         yaml.dump(d, compare=ys)
 
-    def test_rt_root_plain_scalar_no_indent(self):
+    def test_rt_root_plain_scalar_no_indent(self) -> None:
         yaml = YAML()
         yaml.explicit_start = True
         yaml.indent = 0
@@ -270,7 +270,7 @@ class Test_RoundTripLiteral:
         d = yaml.load(ys)
         yaml.dump(d, compare=ys)
 
-    def test_rt_root_plain_scalar_expl_indent(self):
+    def test_rt_root_plain_scalar_expl_indent(self) -> None:
         yaml = YAML()
         yaml.explicit_start = True
         yaml.indent = 4
@@ -283,7 +283,7 @@ class Test_RoundTripLiteral:
         d = yaml.load(ys)
         yaml.dump(d, compare=ys)
 
-    def test_rt_root_sq_scalar_expl_indent(self):
+    def test_rt_root_sq_scalar_expl_indent(self) -> None:
         yaml = YAML()
         yaml.explicit_start = True
         yaml.indent = 4
@@ -296,7 +296,7 @@ class Test_RoundTripLiteral:
         d = yaml.load(ys)
         yaml.dump(d, compare=ys)
 
-    def test_rt_root_dq_scalar_expl_indent(self):
+    def test_rt_root_dq_scalar_expl_indent(self) -> None:
         # if yaml.indent is the default (None)
         # then write after the directive indicator
         yaml = YAML()
@@ -311,7 +311,7 @@ class Test_RoundTripLiteral:
         d = yaml.load(ys)
         yaml.dump(d, compare=ys)
 
-    def test_rt_root_literal_scalar_no_indent_no_eol(self):
+    def test_rt_root_literal_scalar_no_indent_no_eol(self) -> None:
         yaml = YAML()
         yaml.explicit_start = True
         s = 'testing123'
@@ -323,7 +323,7 @@ class Test_RoundTripLiteral:
         d = yaml.load(ys)
         yaml.dump(d, compare=ys)
 
-    def test_rt_non_root_literal_scalar(self):
+    def test_rt_non_root_literal_scalar(self) -> None:
         yaml = YAML()
         s = 'testing123'
         ys = """
diff --git a/_test/test_none.py b/_test/test_none.py
index 42aef4c..e11de17 100644
--- a/_test/test_none.py
+++ b/_test/test_none.py
@@ -1,39 +1,39 @@
 # coding: utf-8
 
-import pytest  # NOQA
+import pytest  # type: ignore  # NOQA
 from roundtrip import round_trip_load, round_trip_dump
 
 
 class TestNone:
-    def test_dump00(self):
+    def test_dump00(self) -> None:
         data = None
         s = round_trip_dump(data)
         assert s == 'null\n...\n'
         d = round_trip_load(s)
         assert d == data
 
-    def test_dump01(self):
+    def test_dump01(self) -> None:
         data = None
         s = round_trip_dump(data, explicit_end=True)
         assert s == 'null\n...\n'
         d = round_trip_load(s)
         assert d == data
 
-    def test_dump02(self):
+    def test_dump02(self) -> None:
         data = None
         s = round_trip_dump(data, explicit_end=False)
         assert s == 'null\n...\n'
         d = round_trip_load(s)
         assert d == data
 
-    def test_dump03(self):
+    def test_dump03(self) -> None:
         data = None
         s = round_trip_dump(data, explicit_start=True)
         assert s == '---\n...\n'
         d = round_trip_load(s)
         assert d == data
 
-    def test_dump04(self):
+    def test_dump04(self) -> None:
         data = None
         s = round_trip_dump(data, explicit_start=True, explicit_end=False)
         assert s == '---\n...\n'
diff --git a/_test/test_numpy.py b/_test/test_numpy.py
index 573f0bd..24eb768 100644
--- a/_test/test_numpy.py
+++ b/_test/test_numpy.py
@@ -1,22 +1,24 @@
 # coding: utf-8
 
-try:
-    import numpy
-except:  # NOQA
-    numpy = None
+#  try:
+#      import numpy
+#  except:  # NOQA
+#      numpy = None
 
 
-def Xtest_numpy():
-    import ruamel.yaml
-
-    if numpy is None:
-        return
-    data = numpy.arange(10)
-    print('data', type(data), data)
-
-    yaml_str = ruamel.yaml.dump(data)
-    datb = ruamel.yaml.load(yaml_str)
-    print('datb', type(datb), datb)
-
-    print('\nYAML', yaml_str)
-    assert data == datb
+#  def Xtest_numpy() -> None:
+#      import ruamel.yaml
+#
+#      if numpy is None:
+#          return
+#      data = numpy.arange(10)
+#      print('data', type(data), data)
+#
+#      buf = io.BytesIO()
+#      ruamel.yaml.dump(data)  # needs updating to use buffer
+#      yaml_str = buf.getvalue().decode('utf-8')
+#      datb = ruamel.yaml.load(yaml_str)
+#      print('datb', type(datb), datb)
+#
+#      print('\nYAML', yaml_str)
+#      assert data == datb
diff --git a/_test/test_program_config.py b/_test/test_program_config.py
index 821ca15..6c5cad8 100644
--- a/_test/test_program_config.py
+++ b/_test/test_program_config.py
@@ -1,13 +1,13 @@
 # coding: utf-8
 
-import pytest  # NOQA
+import pytest  # type: ignore  # NOQA
 
 # import ruamel.yaml
 from roundtrip import round_trip
 
 
 class TestProgramConfig:
-    def test_application_arguments(self):
+    def test_application_arguments(self) -> None:
         # application configur
         round_trip("""
         args:
@@ -20,7 +20,7 @@ class TestProgramConfig:
             wait: 10
         """)
 
-    def test_single(self):
+    def test_single(self) -> None:
         # application configuration
         round_trip("""
         # default arguments for the program
@@ -39,7 +39,7 @@ class TestProgramConfig:
           # no more argument info to pass
         """)
 
-    def test_multi(self):
+    def test_multi(self) -> None:
         # application configuration
         round_trip("""
         # default arguments for the program
diff --git a/_test/test_spec_examples.py b/_test/test_spec_examples.py
index cead787..7faa4bf 100644
--- a/_test/test_spec_examples.py
+++ b/_test/test_spec_examples.py
@@ -1,10 +1,10 @@
 # coding: utf-8
 
 from roundtrip import YAML
-import pytest  # NOQA
+import pytest  # type: ignore  # NOQA
 
 
-def test_example_2_1():
+def test_example_2_1() -> None:
     yaml = YAML()
     yaml.round_trip("""
     - Mark McGwire
@@ -13,8 +13,8 @@ def test_example_2_1():
     """)
 
 
-@pytest.mark.xfail(strict=True)
-def test_example_2_2():
+@pytest.mark.xfail(strict=True)  # type: ignore
+def test_example_2_2() -> None:
     yaml = YAML()
     yaml.mapping_value_align = True
     yaml.round_trip("""
@@ -24,7 +24,7 @@ def test_example_2_2():
     """)
 
 
-def test_example_2_3():
+def test_example_2_3() -> None:
     yaml = YAML()
     yaml.indent(sequence=4, offset=2)
     yaml.round_trip("""
@@ -39,8 +39,8 @@ def test_example_2_3():
     """)
 
 
-@pytest.mark.xfail(strict=True)
-def test_example_2_4():
+@pytest.mark.xfail(strict=True)  # type: ignore
+def test_example_2_4() -> None:
     yaml = YAML()
     yaml.mapping_value_align = True
     yaml.round_trip("""
@@ -55,8 +55,8 @@ def test_example_2_4():
     """)
 
 
-@pytest.mark.xfail(strict=True)
-def test_example_2_5():
+@pytest.mark.xfail(strict=True)  # type: ignore
+def test_example_2_5() -> None:
     yaml = YAML()
     yaml.flow_sequence_element_align = True
     yaml.round_trip("""
@@ -66,8 +66,8 @@ def test_example_2_5():
     """)
 
 
-@pytest.mark.xfail(strict=True)
-def test_example_2_6():
+@pytest.mark.xfail(strict=True)  # type: ignore
+def test_example_2_6() -> None:
     yaml = YAML()
     # yaml.flow_mapping_final_comma = False
     yaml.flow_mapping_one_element_per_line = True
@@ -80,8 +80,8 @@ def test_example_2_6():
     """)
 
 
-@pytest.mark.xfail(strict=True)
-def test_example_2_7():
+@pytest.mark.xfail(strict=True)  # type: ignore
+def test_example_2_7() -> None:
     yaml = YAML()
     yaml.round_trip_all("""
     # Ranking of 1998 home runs
@@ -97,7 +97,7 @@ def test_example_2_7():
     """)
 
 
-def test_example_2_8():
+def test_example_2_8() -> None:
     yaml = YAML()
     yaml.explicit_start = True
     yaml.explicit_end = True
@@ -115,7 +115,7 @@ def test_example_2_8():
     """)
 
 
-def test_example_2_9():
+def test_example_2_9() -> None:
     yaml = YAML()
     yaml.explicit_start = True
     yaml.indent(sequence=4, offset=2)
@@ -131,8 +131,8 @@ def test_example_2_9():
     """)
 
 
-@pytest.mark.xfail(strict=True)
-def test_example_2_10():
+@pytest.mark.xfail(strict=True)  # type: ignore
+def test_example_2_10() -> None:
     yaml = YAML()
     yaml.explicit_start = True
     yaml.indent(sequence=4, offset=2)
@@ -148,8 +148,8 @@ def test_example_2_10():
     """)
 
 
-@pytest.mark.xfail(strict=True)
-def test_example_2_11():
+@pytest.mark.xfail(strict=True)  # type: ignore
+def test_example_2_11() -> None:
     yaml = YAML()
     yaml.round_trip("""
     ? - Detroit Tigers
@@ -164,8 +164,8 @@ def test_example_2_11():
     """)
 
 
-@pytest.mark.xfail(strict=True)
-def test_example_2_12():
+@pytest.mark.xfail(strict=True)  # type: ignore
+def test_example_2_12() -> None:
     yaml = YAML()
     yaml.explicit_start = True
     yaml.round_trip("""
@@ -180,8 +180,8 @@ def test_example_2_12():
     """)
 
 
-@pytest.mark.xfail(strict=True)
-def test_example_2_13():
+@pytest.mark.xfail(strict=True)  # type: ignore
+def test_example_2_13() -> None:
     yaml = YAML()
     yaml.round_trip(r"""
     # ASCII Art
@@ -191,8 +191,8 @@ def test_example_2_13():
     """)
 
 
-@pytest.mark.xfail(strict=True)
-def test_example_2_14():
+@pytest.mark.xfail(strict=True)  # type: ignore
+def test_example_2_14() -> None:
     yaml = YAML()
     yaml.explicit_start = True
     yaml.indent(root_scalar=2)  # needs to be added
@@ -204,8 +204,8 @@ def test_example_2_14():
     """)
 
 
-@pytest.mark.xfail(strict=True)
-def test_example_2_15():
+@pytest.mark.xfail(strict=True)  # type: ignore
+def test_example_2_15() -> None:
     yaml = YAML()
     yaml.round_trip("""
     >
@@ -219,7 +219,7 @@ def test_example_2_15():
     """)
 
 
-def test_example_2_16():
+def test_example_2_16() -> None:
     yaml = YAML()
     yaml.round_trip("""
     name: Mark McGwire
@@ -232,10 +232,10 @@ def test_example_2_16():
     """)
 
 
-@pytest.mark.xfail(
+@pytest.mark.xfail(  # type: ignore
     strict=True, reason='cannot YAML dump escape sequences (\n) as hex and normal'
 )
-def test_example_2_17():
+def test_example_2_17() -> None:
     yaml = YAML()
     yaml.allow_unicode = False
     yaml.preserve_quotes = True
@@ -250,8 +250,9 @@ def test_example_2_17():
     """)
 
 
-@pytest.mark.xfail(strict=True, reason='non-literal/folding multiline scalars not supported')
-def test_example_2_18():
+@pytest.mark.xfail(strict=True,  # type: ignore # NOQA
+                   reason='non-literal/folding multiline scalars not supported')
+def test_example_2_18() -> None:
     yaml = YAML()
     yaml.round_trip("""
     plain:
@@ -263,8 +264,8 @@ def test_example_2_18():
     """)
 
 
-@pytest.mark.xfail(strict=True, reason='leading + on decimal dropped')
-def test_example_2_19():
+@pytest.mark.xfail(strict=True, reason='leading + on decimal dropped')  # type: ignore
+def test_example_2_19() -> None:
     yaml = YAML()
     yaml.round_trip("""
     canonical: 12345
@@ -274,8 +275,8 @@ def test_example_2_19():
     """)
 
 
-@pytest.mark.xfail(strict=True, reason='case of NaN not preserved')
-def test_example_2_20():
+@pytest.mark.xfail(strict=True, reason='case of NaN not preserved')  # type: ignore
+def test_example_2_20() -> None:
     yaml = YAML()
     yaml.round_trip("""
     canonical: 1.23015e+3
@@ -286,7 +287,7 @@ def test_example_2_20():
     """)
 
 
-def Xtest_example_2_X():
+def Xtest_example_2_X() -> None:
     yaml = YAML()
     yaml.round_trip("""
     """)
diff --git a/_test/test_string.py b/_test/test_string.py
index 7c10fd4..75890d2 100644
--- a/_test/test_string.py
+++ b/_test/test_string.py
@@ -13,7 +13,7 @@ and the chomping modifiers:
 
 """
 
-import pytest
+import pytest  # type: ignore
 import platform
 
 # from ruamel.yaml.compat import ordereddict
@@ -21,20 +21,20 @@ from roundtrip import round_trip, dedent, round_trip_load, round_trip_dump  # NO
 
 
 class TestLiteralScalarString:
-    def test_basic_string(self):
+    def test_basic_string(self) -> None:
         round_trip("""
         a: abcdefg
         """)
 
-    def test_quoted_integer_string(self):
+    def test_quoted_integer_string(self) -> None:
         round_trip("""
         a: '12345'
         """)
 
-    @pytest.mark.skipif(
+    @pytest.mark.skipif(  # type: ignore
         platform.python_implementation() == 'Jython', reason='Jython throws RepresenterError'
     )
-    def test_preserve_string(self):
+    def test_preserve_string(self) -> None:
         inp = """
         a: |
           abc
@@ -42,10 +42,10 @@ class TestLiteralScalarString:
         """
         round_trip(inp, intermediate=dict(a='abc\ndef\n'))
 
-    @pytest.mark.skipif(
+    @pytest.mark.skipif(  # type: ignore
         platform.python_implementation() == 'Jython', reason='Jython throws RepresenterError'
     )
-    def test_preserve_string_strip(self):
+    def test_preserve_string_strip(self) -> None:
         s = """
         a: |-
           abc
@@ -54,10 +54,10 @@ class TestLiteralScalarString:
         """
         round_trip(s, intermediate=dict(a='abc\ndef'))
 
-    @pytest.mark.skipif(
+    @pytest.mark.skipif(  # type: ignore
         platform.python_implementation() == 'Jython', reason='Jython throws RepresenterError'
     )
-    def test_preserve_string_keep(self):
+    def test_preserve_string_keep(self) -> None:
         # with pytest.raises(AssertionError) as excinfo:
         inp = """
             a: |+
@@ -69,10 +69,10 @@ class TestLiteralScalarString:
             """
         round_trip(inp, intermediate=dict(a='ghi\njkl\n\n\n', b='x'))
 
-    @pytest.mark.skipif(
+    @pytest.mark.skipif(  # type: ignore
         platform.python_implementation() == 'Jython', reason='Jython throws RepresenterError'
     )
-    def test_preserve_string_keep_at_end(self):
+    def test_preserve_string_keep_at_end(self) -> None:
         # at EOF you have to specify the ... to get proper "closure"
         # of the multiline scalar
         inp = """
@@ -84,7 +84,7 @@ class TestLiteralScalarString:
             """
         round_trip(inp, intermediate=dict(a='ghi\njkl\n\n'))
 
-    def test_fold_string(self):
+    def test_fold_string(self) -> None:
         inp = """
         a: >
           abc
@@ -93,7 +93,7 @@ class TestLiteralScalarString:
         """
         round_trip(inp)
 
-    def test_fold_string_strip(self):
+    def test_fold_string_strip(self) -> None:
         inp = """
         a: >-
           abc
@@ -102,7 +102,7 @@ class TestLiteralScalarString:
         """
         round_trip(inp)
 
-    def test_fold_string_keep(self):
+    def test_fold_string_keep(self) -> None:
         with pytest.raises(AssertionError) as excinfo:  # NOQA
             inp = """
             a: >+
@@ -114,19 +114,19 @@ class TestLiteralScalarString:
 
 
 class TestQuotedScalarString:
-    def test_single_quoted_string(self):
+    def test_single_quoted_string(self) -> None:
         inp = """
         a: 'abc'
         """
         round_trip(inp, preserve_quotes=True)
 
-    def test_double_quoted_string(self):
+    def test_double_quoted_string(self) -> None:
         inp = """
         a: "abc"
         """
         round_trip(inp, preserve_quotes=True)
 
-    def test_non_preserved_double_quoted_string(self):
+    def test_non_preserved_double_quoted_string(self) -> None:
         inp = """
         a: "abc"
         """
@@ -139,7 +139,7 @@ class TestQuotedScalarString:
 class TestReplace:
     """inspired by issue 110 from sandres23"""
 
-    def test_replace_preserved_scalar_string(self):
+    def test_replace_preserved_scalar_string(self) -> None:
         import ruamel
 
         s = dedent("""\
@@ -159,7 +159,7 @@ class TestReplace:
         foo
         """)
 
-    def test_replace_double_quoted_scalar_string(self):
+    def test_replace_double_quoted_scalar_string(self) -> None:
         import ruamel
 
         s = dedent("""\
@@ -172,7 +172,7 @@ class TestReplace:
 
 
 class TestWalkTree:
-    def test_basic(self):
+    def test_basic(self) -> None:
         from ruamel.yaml.comments import CommentedMap
         from ruamel.yaml.scalarstring import walk_tree
 
@@ -188,7 +188,7 @@ class TestWalkTree:
         """
         assert round_trip_dump(data) == dedent(exp)
 
-    def test_map(self):
+    def test_map(self) -> None:
         from ruamel.yaml.compat import ordereddict
         from ruamel.yaml.comments import CommentedMap
         from ruamel.yaml.scalarstring import walk_tree, preserve_literal
diff --git a/_test/test_tag.py b/_test/test_tag.py
index 3fd1e05..bb20621 100644
--- a/_test/test_tag.py
+++ b/_test/test_tag.py
@@ -1,20 +1,21 @@
 # coding: utf-8
 
-import pytest  # NOQA
+import pytest  # type: ignore # NOQA
+from typing import Any
 
 from roundtrip import round_trip, round_trip_load, YAML
 
 
-def register_xxx(**kw):
+def register_xxx(**kw: Any) -> None:
     from ruamel import yaml
 
     class XXX(yaml.comments.CommentedMap):
         @staticmethod
-        def yaml_dump(dumper, data):
+        def yaml_dump(dumper: Any, data: Any) -> Any:
             return dumper.represent_mapping('!xxx', data)
 
         @classmethod
-        def yaml_load(cls, constructor, node):
+        def yaml_load(cls, constructor: Any, node: Any) -> Any:
             data = cls()
             yield data
             constructor.construct_mapping(node, data)
@@ -24,7 +25,7 @@ def register_xxx(**kw):
 
 
 class TestIndentFailures:
-    def test_tag(self):
+    def test_tag(self) -> None:
         round_trip("""\
         !!python/object:__main__.Developer
         name: Anthon
@@ -32,7 +33,7 @@ class TestIndentFailures:
         language: python
         """)
 
-    def test_full_tag(self):
+    def test_full_tag(self) -> None:
         round_trip("""\
         !!tag:yaml.org,2002:python/object:__main__.Developer
         name: Anthon
@@ -40,7 +41,7 @@ class TestIndentFailures:
         language: python
         """)
 
-    def test_standard_tag(self):
+    def test_standard_tag(self) -> None:
         round_trip("""\
         !!tag:yaml.org,2002:python/object:map
         name: Anthon
@@ -48,7 +49,7 @@ class TestIndentFailures:
         language: python
         """)
 
-    def test_Y1(self):
+    def test_Y1(self) -> None:
         round_trip("""\
         !yyy
         name: Anthon
@@ -56,7 +57,7 @@ class TestIndentFailures:
         language: python
         """)
 
-    def test_Y2(self):
+    def test_Y2(self) -> None:
         round_trip("""\
         !!yyy
         name: Anthon
@@ -66,7 +67,7 @@ class TestIndentFailures:
 
 
 class TestRoundTripCustom:
-    def test_X1(self):
+    def test_X1(self) -> None:
         register_xxx()
         round_trip("""\
         !xxx
@@ -75,8 +76,8 @@ class TestRoundTripCustom:
         language: python
         """)
 
-    @pytest.mark.xfail(strict=True)
-    def test_X_pre_tag_comment(self):
+    @pytest.mark.xfail(strict=True)  # type: ignore
+    def test_X_pre_tag_comment(self) -> None:
         register_xxx()
         round_trip("""\
         -
@@ -87,8 +88,8 @@ class TestRoundTripCustom:
           language: python
         """)
 
-    @pytest.mark.xfail(strict=True)
-    def test_X_post_tag_comment(self):
+    @pytest.mark.xfail(strict=True)  # type: ignore
+    def test_X_post_tag_comment(self) -> None:
         register_xxx()
         round_trip("""\
         - !xxx
@@ -98,7 +99,7 @@ class TestRoundTripCustom:
           language: python
         """)
 
-    def test_scalar_00(self):
+    def test_scalar_00(self) -> None:
         # https://stackoverflow.com/a/45967047/1307905
         round_trip("""\
         Outputs:
@@ -110,24 +111,35 @@ class TestRoundTripCustom:
 
 
 class TestIssue201:
-    def test_encoded_unicode_tag(self):
+    def test_encoded_unicode_tag(self) -> None:
         round_trip_load("""
         s: !!python/%75nicode 'abc'
         """)
 
 
 class TestImplicitTaggedNodes:
-    def test_scalar(self):
-        round_trip("""\
-        - !Scalar abcdefg
+    def test_scalar(self) -> None:
+        data = round_trip("""\
+        - !SString abcdefg
+        - !SFloat 1.0
+        - !SInt 1961
+        - !SBool true
+        - !SLit |
+          glitter in the dark near the Tanhäuser gate
         """)
-
-    def test_mapping(self):
+        # tagged scalers have string or string types as value
+        assert data[0].count('d') == 1
+        assert data[1].count('1') == 1
+        assert data[2].count('1') == 2
+        assert data[3].count('u') == 1
+        assert data[4].count('a') == 4
+
+    def test_mapping(self) -> None:
         round_trip("""\
         - !Mapping {a: 1, b: 2}
         """)
 
-    def test_sequence(self):
+    def test_sequence(self) -> None:
         yaml = YAML()
         yaml.brace_single_entry_mapping_in_flow_sequence = True
         yaml.mapping_value_align = True
@@ -135,7 +147,7 @@ class TestImplicitTaggedNodes:
         - !Sequence [a, {b: 1}, {c: {d: 3}}]
         """)
 
-    def test_sequence2(self):
+    def test_sequence2(self) -> None:
         yaml = YAML()
         yaml.mapping_value_align = True
         yaml.round_trip("""
diff --git a/_test/test_version.py b/_test/test_version.py
index e110eed..b60b1dd 100644
--- a/_test/test_version.py
+++ b/_test/test_version.py
@@ -1,11 +1,12 @@
 # coding: utf-8
 
-import pytest  # NOQA
+import pytest  # type: ignore # NOQA
+from typing import Any, Optional
 
 from roundtrip import dedent, round_trip, round_trip_load
 
 
-def load(s, version=None):
+def load(s: str, version: Optional[Any] = None) -> Any:
     import ruamel.yaml  # NOQA
 
     yaml = ruamel.yaml.YAML()
@@ -14,7 +15,7 @@ def load(s, version=None):
 
 
 class TestVersions:
-    def test_explicit_1_2(self):
+    def test_explicit_1_2(self) -> None:
         r = load("""\
         %YAML 1.2
         ---
@@ -38,7 +39,7 @@ class TestVersions:
         assert r[7] == 'no'
         assert r[8] is True
 
-    def test_explicit_1_1(self):
+    def test_explicit_1_1(self) -> None:
         r = load("""\
         %YAML 1.1
         ---
@@ -62,7 +63,7 @@ class TestVersions:
         assert r[7] is False
         assert r[8] is True
 
-    def test_implicit_1_2(self):
+    def test_implicit_1_2(self) -> None:
         r = load("""\
         - 12:34:56
         - 12:34:56.78
@@ -86,7 +87,7 @@ class TestVersions:
         assert r[8] == 'no'
         assert r[9] is True
 
-    def test_load_version_1_1(self):
+    def test_load_version_1_1(self) -> None:
         inp = """\
         - 12:34:56
         - 12:34:56.78
@@ -114,7 +115,7 @@ class TestVersions:
 
 class TestIssue62:
     # bitbucket issue 62, issue_62
-    def test_00(self):
+    def test_00(self) -> None:
         import ruamel.yaml  # NOQA
 
         s = dedent("""\
@@ -131,7 +132,7 @@ class TestIssue62:
             round_trip(s.format('%YAML 1.1\n---\n'), preserve_quotes=True)
         round_trip(s.format(""), preserve_quotes=True)
 
-    def test_00_single_comment(self):
+    def test_00_single_comment(self) -> None:
         import ruamel.yaml  # NOQA
 
         s = dedent("""\
@@ -148,7 +149,7 @@ class TestIssue62:
         round_trip(s.format(""), preserve_quotes=True)
         # round_trip(s.format('%YAML 1.2\n---\n'), preserve_quotes=True, version=(1, 2))
 
-    def test_01(self):
+    def test_01(self) -> None:
         import ruamel.yaml  # NOQA
 
         s = dedent("""\
@@ -160,6 +161,6 @@ class TestIssue62:
         # note the flow seq on the --- line!
         round_trip(s.format('%YAML 1.2\n--- '), preserve_quotes=True, version='1.2')
 
-    def test_so_45681626(self):
+    def test_so_45681626(self) -> None:
         # was not properly parsing
         round_trip_load('{"in":{},"out":{}}')
diff --git a/_test/test_yamlfile.py b/_test/test_yamlfile.py
index f1de872..6f7aca7 100644
--- a/_test/test_yamlfile.py
+++ b/_test/test_yamlfile.py
@@ -6,20 +6,20 @@ various test cases for YAML files
 
 import sys
 import io
-import pytest  # NOQA
+import pytest  # type: ignore # NOQA
 import platform
 
 from roundtrip import round_trip, dedent, round_trip_load, round_trip_dump  # NOQA
 
 
 class TestYAML:
-    def test_backslash(self):
+    def test_backslash(self) -> None:
         round_trip("""
         handlers:
           static_files: applications/\\1/static/\\2
         """)
 
-    def test_omap_out(self):
+    def test_omap_out(self) -> None:
         # ordereddict mapped to !!omap
         from ruamel.yaml.compat import ordereddict
         import ruamel.yaml  # NOQA
@@ -32,7 +32,7 @@ class TestYAML:
         - b: 2
         """)
 
-    def test_omap_roundtrip(self):
+    def test_omap_roundtrip(self) -> None:
         round_trip("""
         !!omap
         - a: 1
@@ -41,25 +41,26 @@ class TestYAML:
         - d: 4
         """)
 
-    @pytest.mark.skipif(sys.version_info < (2, 7), reason='collections not available')
-    def test_dump_collections_ordereddict(self):
-        from collections import OrderedDict
-        import ruamel.yaml  # NOQA
-
-        # OrderedDict mapped to !!omap
-        x = OrderedDict([('a', 1), ('b', 2)])
-        res = round_trip_dump(x, default_flow_style=False)
-        assert res == dedent("""
-        !!omap
-        - a: 1
-        - b: 2
-        """)
-
-    @pytest.mark.skipif(
+    # @pytest.mark.skipif(sys.version_info < (2, 7),
+    #                     reason='collections not available')
+    # def test_dump_collections_ordereddict(self) -> None:
+    #     from collections import OrderedDict
+    #     import ruamel.yaml  # NOQA
+
+    #     # OrderedDict mapped to !!omap
+    #     x = OrderedDict([('a', 1), ('b', 2)])
+    #     res = round_trip_dump(x, default_flow_style=False)
+    #     assert res == dedent("""
+    #     !!omap
+    #     - a: 1
+    #     - b: 2
+    #     """)
+
+    @pytest.mark.skipif(  # type: ignore
         sys.version_info >= (3, 0) or platform.python_implementation() != 'CPython',
         reason='ruamel.yaml not available',
     )
-    def test_dump_ruamel_ordereddict(self):
+    def test_dump_ruamel_ordereddict(self) -> None:
         from ruamel.ordereddict import ordereddict
         import ruamel.yaml  # NOQA
 
@@ -72,7 +73,7 @@ class TestYAML:
         - b: 2
         """)
 
-    def test_CommentedSet(self):
+    def test_CommentedSet(self) -> None:
         from ruamel.yaml.constructor import CommentedSet
 
         s = CommentedSet(['a', 'b', 'c'])
@@ -84,7 +85,7 @@ class TestYAML:
         s.remove('e')
         assert s == CommentedSet(['a', 'c', 'd', 'f'])
 
-    def test_set_out(self):
+    def test_set_out(self) -> None:
         # preferable would be the shorter format without the ': null'
         import ruamel.yaml  # NOQA
 
@@ -102,7 +103,7 @@ class TestYAML:
         """)
 
     # ordering is not preserved in a set
-    def test_set_compact(self):
+    def test_set_compact(self) -> None:
         # this format is read and also should be written by default
         round_trip("""
         !!set
@@ -111,7 +112,7 @@ class TestYAML:
         ? c
         """)
 
-    def test_blank_line_after_comment(self):
+    def test_blank_line_after_comment(self) -> None:
         round_trip("""
         # Comment with spaces after it.
 
@@ -119,7 +120,7 @@ class TestYAML:
         a: 1
         """)
 
-    def test_blank_line_between_seq_items(self):
+    def test_blank_line_between_seq_items(self) -> None:
         round_trip("""
         # Seq with empty lines in between items.
         b:
@@ -129,10 +130,10 @@ class TestYAML:
         - baz
         """)
 
-    @pytest.mark.skipif(
+    @pytest.mark.skipif(  # type: ignore
         platform.python_implementation() == 'Jython', reason='Jython throws RepresenterError'
     )
-    def test_blank_line_after_literal_chip(self):
+    def test_blank_line_after_literal_chip(self) -> None:
         s = """
         c:
         - |
@@ -153,10 +154,10 @@ class TestYAML:
         assert d['c'][0].split('it.')[1] == '\n'
         assert d['c'][1].split('line.')[1] == '\n'
 
-    @pytest.mark.skipif(
+    @pytest.mark.skipif(  # type: ignore
         platform.python_implementation() == 'Jython', reason='Jython throws RepresenterError'
     )
-    def test_blank_line_after_literal_keep(self):
+    def test_blank_line_after_literal_keep(self) -> None:
         """ have to insert an eof marker in YAML to test this"""
         s = """
         c:
@@ -179,10 +180,10 @@ class TestYAML:
         assert d['c'][0].split('it.')[1] == '\n\n'
         assert d['c'][1].split('line.')[1] == '\n\n\n'
 
-    @pytest.mark.skipif(
+    @pytest.mark.skipif(  # type: ignore
         platform.python_implementation() == 'Jython', reason='Jython throws RepresenterError'
     )
-    def test_blank_line_after_literal_strip(self):
+    def test_blank_line_after_literal_strip(self) -> None:
         s = """
         c:
         - |-
@@ -203,7 +204,7 @@ class TestYAML:
         assert d['c'][0].split('it.')[1] == ""
         assert d['c'][1].split('line.')[1] == ""
 
-    def test_load_all_perserve_quotes(self):
+    def test_load_all_perserve_quotes(self) -> None:
         import ruamel.yaml  # NOQA
 
         yaml = ruamel.yaml.YAML()
diff --git a/_test/test_yamlobject.py b/_test/test_yamlobject.py
index 80fb213..3f488d3 100644
--- a/_test/test_yamlobject.py
+++ b/_test/test_yamlobject.py
@@ -1,12 +1,13 @@
 # coding: utf-8
 
 import sys
-import pytest  # NOQA
+from typing import Any
+import pytest  # type: ignore # NOQA
 
 from roundtrip import save_and_run  # NOQA
 
 
-def test_monster(tmpdir):
+def test_monster(tmpdir: Any) -> None:
     program_src = '''\
     import ruamel.yaml
     from textwrap import dedent
@@ -24,27 +25,33 @@ def test_monster(tmpdir):
             return "%s(name=%r, hp=%r, ac=%r, attacks=%r)" % (
                 self.__class__.__name__, self.name, self.hp, self.ac, self.attacks)
 
-    data = ruamel.yaml.load(dedent("""\\
+    yaml = ruamel.yaml.YAML(typ='safe', pure='True')
+    yaml = ruamel.yaml.YAML()
+    data = yaml.load(dedent("""\\
         --- !Monster
         name: Cave spider
         hp: [2,6]    # 2d6
         ac: 16
         attacks: [BITE, HURT]
-    """), Loader=ruamel.yaml.Loader)
+    """))
     # normal dump, keys will be sorted
-    assert ruamel.yaml.dump(data) == dedent("""\\
+    from io import BytesIO
+    buf = BytesIO()
+    yaml.dump(data, buf)
+    print(buf.getvalue().decode('utf-8'))
+    assert buf.getvalue().decode('utf8') == dedent("""\\
         !Monster
+        name: Cave spider
+        hp: [2, 6]   # 2d6
         ac: 16
         attacks: [BITE, HURT]
-        hp: [2, 6]
-        name: Cave spider
     """)
     '''
     assert save_and_run(program_src, tmpdir) == 0
 
 
-@pytest.mark.skipif(sys.version_info < (3, 0), reason='no __qualname__')
-def test_qualified_name00(tmpdir):
+@pytest.mark.skipif(sys.version_info < (3, 0), reason='no __qualname__')  # type: ignore
+def test_qualified_name00(tmpdir: Any) -> None:
     """issue 214"""
     program_src = """\
     from ruamel.yaml import YAML
@@ -67,8 +74,8 @@ def test_qualified_name00(tmpdir):
     assert save_and_run(program_src, tmpdir) == 0
 
 
-@pytest.mark.skipif(sys.version_info < (3, 0), reason='no __qualname__')
-def test_qualified_name01(tmpdir):
+@pytest.mark.skipif(sys.version_info < (3, 0), reason='no __qualname__')  # type: ignore
+def test_qualified_name01(tmpdir: Any) -> None:
     """issue 214"""
     from ruamel.yaml import YAML
     import ruamel.yaml.comments
diff --git a/_test/test_z_check_debug_leftovers.py b/_test/test_z_check_debug_leftovers.py
index f5be5df..7096a73 100644
--- a/_test/test_z_check_debug_leftovers.py
+++ b/_test/test_z_check_debug_leftovers.py
@@ -1,7 +1,8 @@
 # coding: utf-8
 
 import sys
-import pytest  # NOQA
+from typing import Any
+import pytest  # type: ignore # NOQA
 
 from roundtrip import round_trip_load, round_trip_dump, dedent
 
@@ -9,7 +10,7 @@ from roundtrip import round_trip_load, round_trip_dump, dedent
 class TestLeftOverDebug:
     # idea here is to capture round_trip_output via pytest stdout capture
     # if there is are any leftover debug statements they should show up
-    def test_00(self, capsys):
+    def test_00(self, capsys: Any) -> None:
         s = dedent("""
         a: 1
         b: []
@@ -21,7 +22,7 @@ class TestLeftOverDebug:
         out, err = capsys.readouterr()
         assert out == s
 
-    def test_01(self, capsys):
+    def test_01(self, capsys: Any) -> None:
         s = dedent("""
         - 1
         - []
diff --git a/_test/test_z_data.py b/_test/test_z_data.py
index 965eb3d..8a8ba21 100644
--- a/_test/test_z_data.py
+++ b/_test/test_z_data.py
@@ -2,19 +2,18 @@
 
 import sys
 import os
-import pytest  # NOQA
+import pytest  # type: ignore  # NOQA
 import warnings  # NOQA
+from typing import Any, Optional, List, Tuple
 from pathlib import Path
 
-from ruamel.yaml.compat import _F
-
 base_path = Path('data')  # that is ruamel.yaml.data
 
 
-class YAMLData(object):
+class YAMLData:
     yaml_tag = '!YAML'
 
-    def __init__(self, s):
+    def __init__(self, s: Any) -> None:
         self._s = s
 
     # Conversion tables for input. E.g. "<TAB>" is replaced by "\t"
@@ -28,9 +27,9 @@ class YAMLData(object):
     # fmt: on
 
     @property
-    def value(self):
+    def value(self) -> Any:
         if hasattr(self, '_p'):
-            return self._p
+            return self._p  # type: ignore
         assert ' \n' not in self._s
         assert '\t\n' not in self._s
         self._p = self._s
@@ -39,7 +38,7 @@ class YAMLData(object):
             self._p = self._p.replace(k, v)
         return self._p
 
-    def test_rewrite(self, s):
+    def test_rewrite(self, s: str) -> str:
         assert ' \n' not in s
         assert '\t\n' not in s
         for k, v in YAMLData.special.items():
@@ -48,7 +47,7 @@ class YAMLData(object):
         return s
 
     @classmethod
-    def from_yaml(cls, constructor, node):
+    def from_yaml(cls, constructor: Any, node: Any) -> 'YAMLData':
         from ruamel.yaml.nodes import MappingNode
 
         if isinstance(node, MappingNode):
@@ -68,18 +67,18 @@ class Assert(YAMLData):
     yaml_tag = '!Assert'
 
     @property
-    def value(self):
+    def value(self) -> Any:
         from collections.abc import Mapping
 
         if hasattr(self, '_pa'):
-            return self._pa
+            return self._pa  # type: ignore
         if isinstance(self._s, Mapping):
-            self._s['lines'] = self.test_rewrite(self._s['lines'])
+            self._s['lines'] = self.test_rewrite(self._s['lines'])  # type: ignore
         self._pa = self._s
         return self._pa
 
 
-def pytest_generate_tests(metafunc):
+def pytest_generate_tests(metafunc: Any) -> None:
     test_yaml = []
     paths = sorted(base_path.glob('**/*.yaml'))
     idlist = []
@@ -100,8 +99,8 @@ def pytest_generate_tests(metafunc):
     metafunc.parametrize(['yaml'], test_yaml, ids=idlist, scope='class')
 
 
-class TestYAMLData(object):
-    def yaml(self, yaml_version=None):
+class TestYAMLData:
+    def yaml(self, yaml_version: Optional[Any] = None) -> Any:
         from ruamel.yaml import YAML
 
         y = YAML()
@@ -110,7 +109,7 @@ class TestYAMLData(object):
             y.version = yaml_version
         return y
 
-    def docs(self, path):
+    def docs(self, path: Path) -> List[Any]:
         from ruamel.yaml import YAML
 
         tyaml = YAML(typ='safe', pure=True)
@@ -120,12 +119,14 @@ class TestYAMLData(object):
         tyaml.register_class(Assert)
         return list(tyaml.load_all(path))
 
-    def yaml_load(self, value, yaml_version=None):
+    def yaml_load(self, value: Any, yaml_version: Optional[Any] = None) -> Tuple[Any, Any]:
         yaml = self.yaml(yaml_version=yaml_version)
         data = yaml.load(value)
         return yaml, data
 
-    def round_trip(self, input, output=None, yaml_version=None):
+    def round_trip(
+        self, input: Any, output: Optional[Any] = None, yaml_version: Optional[Any] = None
+    ) -> None:
         from ruamel.yaml.compat import StringIO
 
         yaml, data = self.yaml_load(input.value, yaml_version=yaml_version)
@@ -133,9 +134,12 @@ class TestYAMLData(object):
         yaml.dump(data, buf)
         expected = input.value if output is None else output.value
         value = buf.getvalue()
+        print('>>>> rt output\n', value.replace(' ', '\u2423'), sep='')  # 2423 open box
         assert value == expected
 
-    def load_assert(self, input, confirm, yaml_version=None):
+    def load_assert(
+        self, input: Any, confirm: Any, yaml_version: Optional[Any] = None
+    ) -> None:
         from collections.abc import Mapping
 
         d = self.yaml_load(input.value, yaml_version=yaml_version)[1]  # NOQA
@@ -154,14 +158,16 @@ class TestYAMLData(object):
                 print(line)
                 exec(line)
 
-    def run_python(self, python, data, tmpdir, input=None):
+    def run_python(
+        self, python: Any, data: Any, tmpdir: Any, input: Optional[Any] = None
+    ) -> None:
         from roundtrip import save_and_run
 
         if input is not None:
             (tmpdir / 'input.yaml').write_text(input.value, encoding='utf-8')
         assert save_and_run(python.value, base_dir=tmpdir, output=data.value) == 0
 
-    def insert_comments(self, data, actions):
+    def insert_comments(self, data: Any, actions: Any) -> None:
         """this is to automatically insert based on:
           path (a.1.b),
           position (before, after, between), and
@@ -180,7 +186,7 @@ class TestYAMLData(object):
 
     # this is executed by pytest the methods with names not starting with
     # test_ are helper methods
-    def test_yaml_data(self, yaml, tmpdir):
+    def test_yaml_data(self, yaml: Any, tmpdir: Any) -> None:
         from collections.abc import Mapping
 
         idx = 0
@@ -221,8 +227,8 @@ class TestYAMLData(object):
                 typ = 'rt'
         print('type:', typ)
         if data is not None:
-            print('data:', data.value, end='')
-        print('output:', output.value if output is not None else output)
+            print('>>>> data:\n', data.value.replace(' ', '\u2423'), sep='', end='')
+        print('>>>> output:\n', output.value if output is not None else output, sep='')
         if typ == 'rt':
             self.round_trip(data, output, yaml_version=yaml_version)
         elif typ == 'python_run':
@@ -231,14 +237,14 @@ class TestYAMLData(object):
         elif typ == 'load_assert':
             self.load_assert(data, confirm, yaml_version=yaml_version)
         elif typ == 'comment':
-            actions = []
+            actions: List[Any] = []
             self.insert_comments(data, actions)
         else:
-            _F('\n>>>>>> run type unknown: "{typ}" <<<<<<\n')
+            f'\n>>>>>> run type unknown: "{typ}" <<<<<<\n'
             raise AssertionError()
 
 
-def check_python_version(match, current=None):
+def check_python_version(match: Any, current: Optional[Any] = None) -> bool:
     """
     version indication, return True if version matches.
     match should be something like 3.6+, or [2.7, 3.3] etc. Floats
diff --git a/_test/test_z_olddata.py b/_test/test_z_olddata.py
index 89b7053..ffe1572 100644
--- a/_test/test_z_olddata.py
+++ b/_test/test_z_olddata.py
@@ -2,31 +2,33 @@
 
 import sys
 import os
-import pytest  # NOQA
+import pytest  # type: ignore  # NOQA
 
 sys.path.insert(0, os.path.dirname(__file__) + '/lib')
 
 import warnings  # NOQA
 
+from typing import List, Any  # NOQA
 
-args = []
+args: List[Any] = []
 
 
-def test_data():
-    import test_appliance  # NOQA
+def test_data() -> None:
+    import test_appliance  # type: ignore  # NOQA
 
     warnings.simplefilter('ignore', PendingDeprecationWarning)
     collections = []
-    import test_yaml
+    import test_yaml  # type: ignore
 
     collections.append(test_yaml)
     test_appliance.run(collections, args)
 
+
 # @pytest.mark.skipif(not ruamel.yaml.__with_libyaml__,
 #                     reason="no libyaml")
 
 
-def test_data_ext():
+def test_data_ext() -> None:
     collections = []
     import ruamel.yaml  # NOQA
     import test_appliance  # NOQA
@@ -34,7 +36,7 @@ def test_data_ext():
     warnings.simplefilter('ignore', ruamel.yaml.error.UnsafeLoaderWarning)
     warnings.simplefilter('ignore', PendingDeprecationWarning)
     if ruamel.yaml.__with_libyaml__:
-        import test_yaml_ext
+        import test_yaml_ext  # type: ignore
 
         collections.append(test_yaml_ext)
         test_appliance.run(collections, args)