Merge pull request #1489 from RDFLib/hextuples

Hextuples Serializer

43 files changed, 1058 insertions, 199 deletions

diff --git a/.flake8 b/.flake8
index 177f450c..e44a31d2 100644
--- a/.flake8
+++ b/.flake8
@@ -4,3 +4,5 @@ extend-ignore =
     # E501: line too long
     # Disabled so that black can control line length.
     E501,
+    # Ignored since this is soon not going to be considered an error, see https://www.flake8rules.com/rules/W503.html
+    W503,
diff --git a/docs/plugin_parsers.rst b/docs/plugin_parsers.rst
index 81ab7ae6..ed351c0c 100644
--- a/docs/plugin_parsers.rst
+++ b/docs/plugin_parsers.rst
@@ -13,24 +13,35 @@ The ``html`` parser will auto-detect RDFa, HTurtle or Microdata.
 
 It is also possible to pass a mime-type for the ``format`` parameter::
     
-  graph.parse(my_url, format='application/rdf+xml')
+	graph.parse(my_url, format='application/rdf+xml')
 
 If you are not sure what format your file will be, you can use :func:`rdflib.util.guess_format` which will guess based on the file extension. 
 
 ========= ====================================================================
 Name      Class                                                               
 ========= ====================================================================
+json-ld   :class:`~rdflib.plugins.parsers.jsonld.JsonLDParser`
+hext      :class:`~rdflib.plugins.parsers.hext.HextuplesParser`
 html      :class:`~rdflib.plugins.parsers.structureddata.StructuredDataParser`
-hturtle   :class:`~rdflib.plugins.parsers.hturtle.HTurtleParser`
-mdata     :class:`~rdflib.plugins.parsers.structureddata.MicrodataParser`
-microdata :class:`~rdflib.plugins.parsers.structureddata.MicrodataParser`
 n3        :class:`~rdflib.plugins.parsers.notation3.N3Parser`
 nquads    :class:`~rdflib.plugins.parsers.nquads.NQuadsParser`
 nt        :class:`~rdflib.plugins.parsers.ntriples.NTParser`
-rdfa      :class:`~rdflib.plugins.parsers.structureddata.RDFaParser`
-rdfa1.0   :class:`~rdflib.plugins.parsers.structureddata.RDFa10Parser`
-rdfa1.1   :class:`~rdflib.plugins.parsers.structureddata.RDFaParser`
 trix      :class:`~rdflib.plugins.parsers.trix.TriXParser`
 turtle    :class:`~rdflib.plugins.parsers.notation3.TurtleParser`
 xml       :class:`~rdflib.plugins.parsers.rdfxml.RDFXMLParser`
 ========= ====================================================================
+
+Multi-graph IDs
+---------------
+Note that for correct parsing of multi-graph data, e.g. Trig, HexT, etc., into a ``ConjunctiveGraph`` or a ``Dataset``,
+as opposed to a context-unaware ``Graph``, you will need to set the ``publicID`` of the ``ConjunctiveGraph`` a 
+``Dataset`` to the identifier of the ``default_context`` (default graph), for example::
+
+    d = Dataset()
+    d.parse(
+        data=""" ... """, 
+        format="trig", 
+        publicID=d.default_context.identifier
+    )
+
+(from the file tests/test_serializer_hext.py)
diff --git a/docs/plugin_serializers.rst b/docs/plugin_serializers.rst
index 0aedd566..249b0aed 100644
--- a/docs/plugin_serializers.rst
+++ b/docs/plugin_serializers.rst
@@ -11,18 +11,35 @@ passing the name to a graph's :meth:`~rdflib.graph.Graph.serialize` method::
 
 It is also possible to pass a mime-type for the ``format`` parameter::
     
-  graph.serialize(my_url, format='application/rdf+xml')
+	graph.serialize(my_url, format='application/rdf+xml')
 
 ========== ===============================================================
 Name       Class                                                          
 ========== ===============================================================
+json-ld    :class:`~rdflib.plugins.serializers.jsonld.JsonLDSerializer`
 n3         :class:`~rdflib.plugins.serializers.n3.N3Serializer`
 nquads     :class:`~rdflib.plugins.serializers.nquads.NQuadsSerializer`
 nt         :class:`~rdflib.plugins.serializers.nt.NTSerializer`
+hext       :class:`~rdflib.plugins.serializers.hext.HextuplesSerializer`
 pretty-xml :class:`~rdflib.plugins.serializers.rdfxml.PrettyXMLSerializer`
 trig       :class:`~rdflib.plugins.serializers.trig.TrigSerializer`
 trix       :class:`~rdflib.plugins.serializers.trix.TriXSerializer`
 turtle     :class:`~rdflib.plugins.serializers.turtle.TurtleSerializer`
+longturtle :class:`~rdflib.plugins.serializers.turtle.LongTurtleSerializer`
 xml        :class:`~rdflib.plugins.serializers.rdfxml.XMLSerializer`
 ========== ===============================================================
 
+
+JSON-LD
+-------
+JSON-LD - 'json-ld' - has been incorprated in rdflib since v6.0.0.
+
+HexTuples
+---------
+The HexTuples Serializer - 'hext' - uses the HexTuples format defined at https://github.com/ontola/hextuples.
+
+For serialization of non-context-aware data sources, e.g. a single ``Graph``, the 'graph' field (6th variable in the 
+Hextuple) will be an empty string.
+
+For context-aware (multi-graph) serialization, the 'graph' field of the default graph will be an empty string and 
+the values for other graphs will be Blank Node IDs or IRIs.
diff --git a/rdflib/__init__.py b/rdflib/__init__.py
index 9b8daeb0..10541861 100644
--- a/rdflib/__init__.py
+++ b/rdflib/__init__.py
@@ -45,7 +45,7 @@ A tiny example:
 __docformat__ = "restructuredtext en"
 
 # The format of the __version__ line is matched by a regex in setup.py
-__version__ = "6.03a"
+__version__ = "6.0.3"
 __date__ = "2021-10-10"
 
 __all__ = [
diff --git a/rdflib/compare.py b/rdflib/compare.py
index 16994fa7..f8256439 100644
--- a/rdflib/compare.py
+++ b/rdflib/compare.py
@@ -428,7 +428,6 @@ class _TripleCanonicalizer(object):
         candidates = self._get_candidates(coloring)
         best: List[List[Color]] = []
         best_score = None
-        best_experimental = None
         best_experimental_score = None
         last_coloring = None
         generator: Dict[Node, Set[Node]] = defaultdict(set)
diff --git a/rdflib/namespace/__init__.py b/rdflib/namespace/__init__.py
index 4b76366f..8ce4de79 100644
--- a/rdflib/namespace/__init__.py
+++ b/rdflib/namespace/__init__.py
@@ -81,7 +81,6 @@ The following namespaces are available by directly importing from rdflib:
 
 __all__ = ["is_ncname", "split_uri", "Namespace", "ClosedNamespace", "NamespaceManager"]
 
-
 logger = logging.getLogger(__name__)
 
 
@@ -192,7 +191,7 @@ class DefinedNamespaceMeta(type):
         name = str(name)
         if str(name).startswith("__"):
             return super().__getitem__(name, default)
-        if (cls._warn or cls._fail) and not name in cls:
+        if (cls._warn or cls._fail) and name not in cls:
             if cls._fail:
                 raise AttributeError(f"term '{name}' not in namespace '{cls._NS}'")
             else:
diff --git a/rdflib/parser.py b/rdflib/parser.py
index 2a2875d9..8437a2e7 100644
--- a/rdflib/parser.py
+++ b/rdflib/parser.py
@@ -341,8 +341,7 @@ def create_input_source(
             input_source = StringInputSource(data)
             auto_close = True
         else:
-            raise RuntimeError(
-                f"parse data can only str, or bytes. not: {type(data)}")
+            raise RuntimeError(f"parse data can only str, or bytes. not: {type(data)}")
 
     if input_source is None:
         raise Exception("could not create InputSource")
diff --git a/rdflib/plugin.py b/rdflib/plugin.py
index c5ffd093..b7edbc62 100644
--- a/rdflib/plugin.py
+++ b/rdflib/plugin.py
@@ -169,16 +169,54 @@ def plugins(
             yield p
 
 
-# Register Store Plugins
-register("default", Store, "rdflib.plugins.stores.memory", "Memory")
-register("Memory", Store, "rdflib.plugins.stores.memory", "Memory")
-register("SimpleMemory", Store, "rdflib.plugins.stores.memory", "SimpleMemory")
-register("Auditable", Store, "rdflib.plugins.stores.auditable", "AuditableStore")
-register("Concurrent", Store, "rdflib.plugins.stores.concurrent", "ConcurrentStore")
-register("BerkeleyDB", Store, "rdflib.plugins.stores.berkeleydb", "BerkeleyDB")
-register("SPARQLStore", Store, "rdflib.plugins.stores.sparqlstore", "SPARQLStore")
+# Register Stores
 register(
-    "SPARQLUpdateStore", Store, "rdflib.plugins.stores.sparqlstore", "SPARQLUpdateStore"
+    "default",
+    Store,
+    "rdflib.plugins.stores.memory",
+    "Memory",
+)
+register(
+    "Memory",
+    Store,
+    "rdflib.plugins.stores.memory",
+    "Memory",
+)
+register(
+    "SimpleMemory",
+    Store,
+    "rdflib.plugins.stores.memory",
+    "SimpleMemory",
+)
+register(
+    "Auditable",
+    Store,
+    "rdflib.plugins.stores.auditable",
+    "AuditableStore",
+)
+register(
+    "Concurrent",
+    Store,
+    "rdflib.plugins.stores.concurrent",
+    "ConcurrentStore",
+)
+register(
+    "BerkeleyDB",
+    Store,
+    "rdflib.plugins.stores.berkeleydb",
+    "BerkeleyDB",
+)
+register(
+    "SPARQLStore",
+    Store,
+    "rdflib.plugins.stores.sparqlstore",
+    "SPARQLStore",
+)
+register(
+    "SPARQLUpdateStore",
+    Store,
+    "rdflib.plugins.stores.sparqlstore",
+    "SPARQLUpdateStore",
 )
 
 # Register Triple Serializers
@@ -188,25 +226,84 @@ register(
     "rdflib.plugins.serializers.rdfxml",
     "XMLSerializer",
 )
-register("xml", Serializer, "rdflib.plugins.serializers.rdfxml", "XMLSerializer")
 register(
-    "pretty-xml", Serializer, "rdflib.plugins.serializers.rdfxml", "PrettyXMLSerializer"
+    "xml",
+    Serializer,
+    "rdflib.plugins.serializers.rdfxml",
+    "XMLSerializer",
+)
+register(
+    "pretty-xml",
+    Serializer,
+    "rdflib.plugins.serializers.rdfxml",
+    "PrettyXMLSerializer",
+)
+register(
+    "text/n3",
+    Serializer,
+    "rdflib.plugins.serializers.n3",
+    "N3Serializer",
+)
+register(
+    "n3",
+    Serializer,
+    "rdflib.plugins.serializers.n3",
+    "N3Serializer",
+)
+register(
+    "text/turtle",
+    Serializer,
+    "rdflib.plugins.serializers.turtle",
+    "TurtleSerializer",
+)
+register(
+    "turtle",
+    Serializer,
+    "rdflib.plugins.serializers.turtle",
+    "TurtleSerializer",
+)
+register(
+    "ttl",
+    Serializer,
+    "rdflib.plugins.serializers.turtle",
+    "TurtleSerializer",
 )
-register("text/n3", Serializer, "rdflib.plugins.serializers.n3", "N3Serializer")
-register("n3", Serializer, "rdflib.plugins.serializers.n3", "N3Serializer")
 register(
-    "text/turtle", Serializer, "rdflib.plugins.serializers.turtle", "TurtleSerializer"
+    "longturtle",
+    Serializer,
+    "rdflib.plugins.serializers.longturtle",
+    "LongTurtleSerializer",
 )
-register("turtle", Serializer, "rdflib.plugins.serializers.turtle", "TurtleSerializer")
-register("turtle2", Serializer, "rdflib.plugins.serializers.turtle2", "TurtleSerializer2")
-register("ttl", Serializer, "rdflib.plugins.serializers.turtle", "TurtleSerializer")
 register(
-    "application/n-triples", Serializer, "rdflib.plugins.serializers.nt", "NTSerializer"
+    "application/n-triples",
+    Serializer,
+    "rdflib.plugins.serializers.nt",
+    "NTSerializer",
+)
+register(
+    "ntriples",
+    Serializer,
+    "rdflib.plugins.serializers.nt",
+    "NTSerializer",
+)
+register(
+    "nt",
+    Serializer,
+    "rdflib.plugins.serializers.nt",
+    "NTSerializer",
+)
+register(
+    "nt11",
+    Serializer,
+    "rdflib.plugins.serializers.nt",
+    "NT11Serializer",
+)
+register(
+    "json-ld",
+    Serializer,
+    "rdflib.plugins.serializers.jsonld",
+    "JsonLDSerializer",
 )
-register("ntriples", Serializer, "rdflib.plugins.serializers.nt", "NTSerializer")
-register("nt", Serializer, "rdflib.plugins.serializers.nt", "NTSerializer")
-register("nt11", Serializer, "rdflib.plugins.serializers.nt", "NT11Serializer")
-register("json-ld", Serializer, "rdflib.plugins.serializers.jsonld", "JsonLDSerializer")
 register(
     "application/ld+json",
     Serializer,
@@ -221,43 +318,180 @@ register(
     "rdflib.plugins.serializers.nquads",
     "NQuadsSerializer",
 )
-register("nquads", Serializer, "rdflib.plugins.serializers.nquads", "NQuadsSerializer")
 register(
-    "application/trix", Serializer, "rdflib.plugins.serializers.trix", "TriXSerializer"
+    "nquads",
+    Serializer,
+    "rdflib.plugins.serializers.nquads",
+    "NQuadsSerializer",
 )
-register("trix", Serializer, "rdflib.plugins.serializers.trix", "TriXSerializer")
 register(
-    "application/trig", Serializer, "rdflib.plugins.serializers.trig", "TrigSerializer"
+    "application/trix",
+    Serializer,
+    "rdflib.plugins.serializers.trix",
+    "TriXSerializer",
+)
+register(
+    "trix",
+    Serializer,
+    "rdflib.plugins.serializers.trix",
+    "TriXSerializer",
+)
+register(
+    "application/trig",
+    Serializer,
+    "rdflib.plugins.serializers.trig",
+    "TrigSerializer",
+)
+register(
+    "trig",
+    Serializer,
+    "rdflib.plugins.serializers.trig",
+    "TrigSerializer",
+)
+register(
+    "hext",
+    Serializer,
+    "rdflib.plugins.serializers.hext",
+    "HextuplesSerializer",
 )
-register("trig", Serializer, "rdflib.plugins.serializers.trig", "TrigSerializer")
 
 # Register Triple Parsers
-register("application/rdf+xml", Parser, "rdflib.plugins.parsers.rdfxml", "RDFXMLParser")
-register("xml", Parser, "rdflib.plugins.parsers.rdfxml", "RDFXMLParser")
-register("text/n3", Parser, "rdflib.plugins.parsers.notation3", "N3Parser")
-register("n3", Parser, "rdflib.plugins.parsers.notation3", "N3Parser")
-register("text/turtle", Parser, "rdflib.plugins.parsers.notation3", "TurtleParser")
-register("turtle", Parser, "rdflib.plugins.parsers.notation3", "TurtleParser")
-register("ttl", Parser, "rdflib.plugins.parsers.notation3", "TurtleParser")
-register("application/n-triples", Parser, "rdflib.plugins.parsers.ntriples", "NTParser")
-register("ntriples", Parser, "rdflib.plugins.parsers.ntriples", "NTParser")
-register("nt", Parser, "rdflib.plugins.parsers.ntriples", "NTParser")
-register("nt11", Parser, "rdflib.plugins.parsers.ntriples", "NTParser")
-register("application/ld+json", Parser, "rdflib.plugins.parsers.jsonld", "JsonLDParser")
-register("json-ld", Parser, "rdflib.plugins.parsers.jsonld", "JsonLDParser")
-
+register(
+    "application/rdf+xml",
+    Parser,
+    "rdflib.plugins.parsers.rdfxml",
+    "RDFXMLParser",
+)
+register(
+    "xml",
+    Parser,
+    "rdflib.plugins.parsers.rdfxml",
+    "RDFXMLParser",
+)
+register(
+    "text/n3",
+    Parser,
+    "rdflib.plugins.parsers.notation3",
+    "N3Parser",
+)
+register(
+    "n3",
+    Parser,
+    "rdflib.plugins.parsers.notation3",
+    "N3Parser",
+)
+register(
+    "text/turtle",
+    Parser,
+    "rdflib.plugins.parsers.notation3",
+    "TurtleParser",
+)
+register(
+    "turtle",
+    Parser,
+    "rdflib.plugins.parsers.notation3",
+    "TurtleParser",
+)
+register(
+    "ttl",
+    Parser,
+    "rdflib.plugins.parsers.notation3",
+    "TurtleParser",
+)
+register(
+    "application/n-triples",
+    Parser,
+    "rdflib.plugins.parsers.ntriples",
+    "NTParser",
+)
+register(
+    "ntriples",
+    Parser,
+    "rdflib.plugins.parsers.ntriples",
+    "NTParser",
+)
+register(
+    "nt",
+    Parser,
+    "rdflib.plugins.parsers.ntriples",
+    "NTParser",
+)
+register(
+    "nt11",
+    Parser,
+    "rdflib.plugins.parsers.ntriples",
+    "NTParser",
+)
+register(
+    "application/ld+json",
+    Parser,
+    "rdflib.plugins.parsers.jsonld",
+    "JsonLDParser",
+)
+register(
+    "json-ld",
+    Parser,
+    "rdflib.plugins.parsers.jsonld",
+    "JsonLDParser",
+)
 
 # Register Quad Parsers
-register("application/n-quads", Parser, "rdflib.plugins.parsers.nquads", "NQuadsParser")
-register("nquads", Parser, "rdflib.plugins.parsers.nquads", "NQuadsParser")
-register("application/trix", Parser, "rdflib.plugins.parsers.trix", "TriXParser")
-register("trix", Parser, "rdflib.plugins.parsers.trix", "TriXParser")
-register("application/trig", Parser, "rdflib.plugins.parsers.trig", "TrigParser")
-register("trig", Parser, "rdflib.plugins.parsers.trig", "TrigParser")
+register(
+    "application/n-quads",
+    Parser,
+    "rdflib.plugins.parsers.nquads",
+    "NQuadsParser",
+)
+register(
+    "nquads",
+    Parser,
+    "rdflib.plugins.parsers.nquads",
+    "NQuadsParser",
+)
+register(
+    "application/trix",
+    Parser,
+    "rdflib.plugins.parsers.trix",
+    "TriXParser",
+)
+register(
+    "trix",
+    Parser,
+    "rdflib.plugins.parsers.trix",
+    "TriXParser",
+)
+register(
+    "application/trig",
+    Parser,
+    "rdflib.plugins.parsers.trig",
+    "TrigParser",
+)
+register(
+    "trig",
+    Parser,
+    "rdflib.plugins.parsers.trig",
+    "TrigParser",
+)
+register(
+    "hext",
+    Parser,
+    "rdflib.plugins.parsers.hext",
+    "HextuplesParser",
+)
 
 # Register SPARQL Processors
-register("sparql", Result, "rdflib.plugins.sparql.processor", "SPARQLResult")
-register("sparql", Processor, "rdflib.plugins.sparql.processor", "SPARQLProcessor")
+register(
+    "sparql",
+    Result,
+    "rdflib.plugins.sparql.processor",
+    "SPARQLResult",
+)
+register(
+    "sparql",
+    Processor,
+    "rdflib.plugins.sparql.processor",
+    "SPARQLProcessor",
+)
 register(
     "sparql",
     UpdateProcessor,
@@ -311,7 +545,10 @@ register(
 
 # Register SPARQL Result Parsers
 register(
-    "xml", ResultParser, "rdflib.plugins.sparql.results.xmlresults", "XMLResultParser"
+    "xml",
+    ResultParser,
+    "rdflib.plugins.sparql.results.xmlresults",
+    "XMLResultParser",
 )
 register(
     "application/sparql-results+xml",
@@ -344,7 +581,10 @@ register(
     "JSONResultParser",
 )
 register(
-    "csv", ResultParser, "rdflib.plugins.sparql.results.csvresults", "CSVResultParser"
+    "csv",
+    ResultParser,
+    "rdflib.plugins.sparql.results.csvresults",
+    "CSVResultParser",
 )
 register(
     "text/csv",
@@ -353,7 +593,10 @@ register(
     "CSVResultParser",
 )
 register(
-    "tsv", ResultParser, "rdflib.plugins.sparql.results.tsvresults", "TSVResultParser"
+    "tsv",
+    ResultParser,
+    "rdflib.plugins.sparql.results.tsvresults",
+    "TSVResultParser",
 )
 register(
     "text/tab-separated-values",
diff --git a/rdflib/plugins/parsers/hext.py b/rdflib/plugins/parsers/hext.py
new file mode 100644
index 00000000..59e045cf
--- /dev/null
+++ b/rdflib/plugins/parsers/hext.py
@@ -0,0 +1,88 @@
+"""
+This is a rdflib plugin for parsing Hextuple files, which are Newline-Delimited JSON
+(ndjson) files, into Conjunctive. The store that backs the graph *must* be able to
+handle contexts, i.e. multiple graphs.
+"""
+import json
+
+from typing import List, Union
+from rdflib.parser import Parser
+from rdflib import ConjunctiveGraph, URIRef, Literal, BNode
+import warnings
+
+
+__all__ = ["HextuplesParser"]
+
+
+class HextuplesParser(Parser):
+    """
+    An RDFLib parser for Hextuples
+
+    """
+
+    def __init__(self):
+        pass
+
+    def _load_json_line(self, line: str):
+        return [x if x != "" else None for x in json.loads(line)]
+
+    def _parse_hextuple(self, cg: ConjunctiveGraph, tup: List[Union[str, None]]):
+        # all values check
+        # subject, predicate, value, datatype cannot be None
+        # language and graph may be None
+        if tup[0] is None or tup[1] is None or tup[2] is None or tup[3] is None:
+            raise ValueError("subject, predicate, value, datatype cannot be None")
+
+        # 1 - subject
+        s: Union[URIRef, BNode]
+        if tup[0].startswith("_"):
+            s = BNode(value=tup[0].replace("_:", ""))
+        else:
+            s = URIRef(tup[0])
+
+        # 2 - predicate
+        p = URIRef(tup[1])
+
+        # 3 - value
+        o: Union[URIRef, BNode, Literal]
+        if tup[3] == "globalId":
+            o = URIRef(tup[2])
+        elif tup[3] == "localId":
+            o = BNode(value=tup[2].replace("_:", ""))
+        else:  # literal
+            if tup[4] is None:
+                o = Literal(tup[2], datatype=URIRef(tup[3]))
+            else:
+                o = Literal(tup[2], lang=tup[4])
+
+        # 6 - context
+        if tup[5] is not None:
+            c = URIRef(tup[5])
+            cg.add((s, p, o, c))
+        else:
+            cg.add((s, p, o))
+
+    def parse(self, source, graph, **kwargs):
+        if kwargs.get("encoding") not in [None, "utf-8"]:
+            warnings.warn(
+                f"Hextuples files are always utf-8 encoded, "
+                f"I was passed: {kwargs.get('encoding')}, "
+                "but I'm still going to use utf-8"
+            )
+
+        assert (
+            graph.store.context_aware
+        ), "Hextuples Parser needs a context-aware store!"
+
+        cg = ConjunctiveGraph(store=graph.store, identifier=graph.identifier)
+        cg.default_context = graph
+
+        # handle different source types - only file and string (data) for now
+        if hasattr(source, "file"):
+            with open(source.file.name) as fp:
+                for l in fp:
+                    self._parse_hextuple(cg, self._load_json_line(l))
+        elif hasattr(source, "_InputSource__bytefile"):
+            if hasattr(source._InputSource__bytefile, "wrapped"):
+                for l in source._InputSource__bytefile.wrapped.strip().splitlines():
+                    self._parse_hextuple(cg, self._load_json_line(l))
diff --git a/rdflib/plugins/parsers/jsonld.py b/rdflib/plugins/parsers/jsonld.py
index 77fa8b4d..c816947a 100644
--- a/rdflib/plugins/parsers/jsonld.py
+++ b/rdflib/plugins/parsers/jsonld.py
@@ -94,7 +94,7 @@ class JsonLDParser(rdflib.parser.Parser):
         if encoding not in ("utf-8", "utf-16"):
             warnings.warn(
                 "JSON should be encoded as unicode. "
-                + "Given encoding was: %s" % encoding
+                "Given encoding was: %s" % encoding
             )
 
         base = kwargs.get("base") or sink.absolutize(
diff --git a/rdflib/plugins/parsers/notation3.py b/rdflib/plugins/parsers/notation3.py
index cfdc8568..31b20036 100755
--- a/rdflib/plugins/parsers/notation3.py
+++ b/rdflib/plugins/parsers/notation3.py
@@ -43,7 +43,6 @@ from rdflib.exceptions import ParserError
 from rdflib.term import URIRef, BNode, Literal, Variable, _XSD_PFX, _unique_id
 from rdflib.graph import QuotedGraph, ConjunctiveGraph, Graph
 from rdflib.compat import long_type
-from rdflib.compat import narrow_build
 
 __all__ = [
     "BadSyntax",
@@ -327,7 +326,7 @@ unicodeEscape8 = re.compile(r"\\U([0-9a-fA-F]{8})")
 
 N3CommentCharacter = "#"  # For unix script  # ! compatibility
 
-########################################## Parse string to sink
+# Parse string to sink
 #
 # Regular expressions:
 eol = re.compile(r"[ \t]*(#[^\n]*)?\r?\n")  # end  of line, poss. w/comment
@@ -604,10 +603,7 @@ class SinkParser:
                 self.BadSyntax(
                     argstr,
                     j,
-                    "With no base URI, cannot use "
-                    + "relative URI in @prefix <"
-                    + ns
-                    + ">",
+                    f"With no base URI, cannot use relative URI in @prefix <{ns}>",
                 )
             assert ":" in ns  # must be absolute
             self._bindings[t[0][0]] = ns
diff --git a/rdflib/plugins/parsers/ntriples.py b/rdflib/plugins/parsers/ntriples.py
index 9a66df7f..5e9ab7c8 100644
--- a/rdflib/plugins/parsers/ntriples.py
+++ b/rdflib/plugins/parsers/ntriples.py
@@ -54,7 +54,6 @@ r_uniquot = re.compile(r"\\u([0-9A-F]{4})|\\U([0-9A-F]{8})")
 def unquote(s):
     """Unquote an N-Triples string."""
     if not validate:
-
         if isinstance(s, str):  # nquads
             s = decodeUnicodeEscape(s)
         else:
diff --git a/rdflib/plugins/serializers/hext.py b/rdflib/plugins/serializers/hext.py
new file mode 100644
index 00000000..c86882a2
--- /dev/null
+++ b/rdflib/plugins/serializers/hext.py
@@ -0,0 +1,131 @@
+"""
+HextuplesSerializer RDF graph serializer for RDFLib.
+See <https://github.com/ontola/hextuples> for details about the format.
+"""
+from typing import IO, Optional, Union
+from rdflib.graph import Graph, ConjunctiveGraph
+from rdflib.term import Literal, URIRef, Node, BNode
+from rdflib.serializer import Serializer
+from rdflib.namespace import RDF, XSD
+import warnings
+
+__all__ = ["HextuplesSerializer"]
+
+
+class HextuplesSerializer(Serializer):
+    """
+    Serializes RDF graphs to NTriples format.
+    """
+
+    def __init__(self, store: Union[Graph, ConjunctiveGraph]):
+        self.default_context: Optional[Node]
+        if isinstance(store, ConjunctiveGraph):
+            self.contexts = list(store.contexts())
+            if store.default_context:
+                self.default_context = store.default_context
+                self.contexts.append(store.default_context)
+            else:
+                self.default_context = None
+        else:
+            self.contexts = [store]
+            self.default_context = None
+
+        Serializer.__init__(self, store)
+
+    def serialize(
+        self,
+        stream: IO[bytes],
+        base: Optional[str] = None,
+        encoding: Optional[str] = "utf-8",
+        **kwargs,
+    ):
+        if base is not None:
+            warnings.warn(
+                "base has no meaning for Hextuples serialization. "
+                "I will ignore this value"
+            )
+
+        if encoding not in [None, "utf-8"]:
+            warnings.warn(
+                f"Hextuples files are always utf-8 encoded. "
+                f"I was passed: {encoding}, "
+                "but I'm still going to use utf-8 anyway!"
+            )
+
+        if self.store.formula_aware is True:
+            raise Exception(
+                "Hextuple serialization can't (yet) handle formula-aware stores"
+            )
+
+        for context in self.contexts:
+            for triple in context:
+                hl = self._hex_line(triple, context)
+                if hl is not None:
+                    stream.write(hl.encode())
+
+    def _hex_line(self, triple, context):
+        if isinstance(
+            triple[0], (URIRef, BNode)
+        ):  # exclude QuotedGraph and other objects
+            # value
+            value = (
+                triple[2]
+                if isinstance(triple[2], Literal)
+                else self._iri_or_bn(triple[2])
+            )
+
+            # datatype
+            if isinstance(triple[2], URIRef):
+                # datatype = "http://www.w3.org/1999/02/22-rdf-syntax-ns#namedNode"
+                datatype = "globalId"
+            elif isinstance(triple[2], BNode):
+                # datatype = "http://www.w3.org/1999/02/22-rdf-syntax-ns#blankNode"
+                datatype = "localId"
+            elif isinstance(triple[2], Literal):
+                if triple[2].datatype is not None:
+                    datatype = f"{triple[2].datatype}"
+                else:
+                    if triple[2].language is not None:  # language
+                        datatype = RDF.langString
+                    else:
+                        datatype = XSD.string
+            else:
+                return None  # can't handle non URI, BN or Literal Object (QuotedGraph)
+
+            # language
+            if isinstance(triple[2], Literal):
+                if triple[2].language is not None:
+                    language = f"{triple[2].language}"
+                else:
+                    language = ""
+            else:
+                language = ""
+
+            return '["%s", "%s", "%s", "%s", "%s", "%s"]\n' % (
+                self._iri_or_bn(triple[0]),
+                triple[1],
+                value,
+                datatype,
+                language,
+                self._context(context),
+            )
+        else:  # do not return anything for non-IRIs or BNs, e.g. QuotedGraph, Subjects
+            return None
+
+    def _iri_or_bn(self, i_):
+        if isinstance(i_, URIRef):
+            return f"{i_}"
+        elif isinstance(i_, BNode):
+            return f"{i_.n3()}"
+        else:
+            return None
+
+    def _context(self, context):
+        if self.default_context is None:
+            return ""
+        if context.identifier == "urn:x-rdflib:default":
+            return ""
+        elif context is not None and self.default_context is not None:
+            if context.identifier == self.default_context.identifier:
+                return ""
+        return context.identifier
diff --git a/rdflib/plugins/serializers/jsonld.py b/rdflib/plugins/serializers/jsonld.py
index f5067e28..002f04f7 100644
--- a/rdflib/plugins/serializers/jsonld.py
+++ b/rdflib/plugins/serializers/jsonld.py
@@ -62,7 +62,7 @@ class JsonLDSerializer(Serializer):
         stream: IO[bytes],
         base: Optional[str] = None,
         encoding: Optional[str] = None,
-        **kwargs
+        **kwargs,
     ):
         # TODO: docstring w. args and return value
         encoding = encoding or "utf-8"
@@ -364,18 +364,18 @@ class Converter(object):
             else:
                 return v
 
-    def to_collection(self, graph, l):
-        if l != RDF.nil and not graph.value(l, RDF.first):
+    def to_collection(self, graph, l_):
+        if l_ != RDF.nil and not graph.value(l_, RDF.first):
             return None
         list_nodes = []
-        chain = set([l])
-        while l:
-            if l == RDF.nil:
+        chain = set([l_])
+        while l_:
+            if l_ == RDF.nil:
                 return list_nodes
-            if isinstance(l, URIRef):
+            if isinstance(l_, URIRef):
                 return None
             first, rest = None, None
-            for p, o in graph.predicate_objects(l):
+            for p, o in graph.predicate_objects(l_):
                 if not first and p == RDF.first:
                     first = o
                 elif not rest and p == RDF.rest:
@@ -383,7 +383,7 @@ class Converter(object):
                 elif p != RDF.type or o != RDF.List:
                     return None
             list_nodes.append(first)
-            l = rest
-            if l in chain:
+            l_ = rest
+            if l_ in chain:
                 return None
-            chain.add(l)
+            chain.add(l_)
diff --git a/rdflib/plugins/serializers/turtle2.py b/rdflib/plugins/serializers/longturtle.py
index 49e9cbad..0d50e47a 100644
--- a/rdflib/plugins/serializers/turtle2.py
+++ b/rdflib/plugins/serializers/longturtle.py
@@ -1,8 +1,8 @@
 """
-Turtle2 RDF graph serializer for RDFLib.
+LongTurtle RDF graph serializer for RDFLib.
 See <http://www.w3.org/TeamSubmission/turtle/> for syntax specification.
 
-This variant, turtle2 as opposed to just turtle, makes some small format changes
+This variant, longturtle as opposed to just turtle, makes some small format changes
 to turtle - the original turtle serializer. It:
 
 * uses PREFIX instead of @prefix
@@ -21,7 +21,7 @@ from rdflib.exceptions import Error
 from .turtle import RecursiveSerializer
 from rdflib.namespace import RDF
 
-__all__ = ["TurtleSerializer2"]
+__all__ = ["LongTurtleSerializer"]
 
 SUBJECT = 0
 VERB = 1
@@ -31,14 +31,14 @@ _GEN_QNAME_FOR_DT = False
 _SPACIOUS_OUTPUT = False
 
 
-class TurtleSerializer2(RecursiveSerializer):
+class LongTurtleSerializer(RecursiveSerializer):
 
-    short_name = "turtle2"
+    short_name = "longturtle"
     indentString = "    "
 
     def __init__(self, store):
         self._ns_rewrite = {}
-        super(TurtleSerializer2, self).__init__(store)
+        super(LongTurtleSerializer, self).__init__(store)
         self.keywords = {RDF.type: "a"}
         self.reset()
         self.stream = None
@@ -66,11 +66,11 @@ class TurtleSerializer2(RecursiveSerializer):
 
             prefix = self._ns_rewrite.get(prefix, prefix)
 
-        super(TurtleSerializer2, self).addNamespace(prefix, namespace)
+        super(LongTurtleSerializer, self).addNamespace(prefix, namespace)
         return prefix
 
     def reset(self):
-        super(TurtleSerializer2, self).reset()
+        super(LongTurtleSerializer, self).reset()
         self._shortNames = {}
         self._started = False
         self._ns_rewrite = {}
@@ -78,7 +78,7 @@ class TurtleSerializer2(RecursiveSerializer):
     def serialize(self, stream, base=None, encoding=None, spacious=None, **args):
         self.reset()
         self.stream = stream
-        # if base is given here, use that, if not and a base is set for the graph use that
+        # if base is given here, use, if not and a base is set for the graph use that
         if base is not None:
             self.base = base
         elif self.store.base is not None:
@@ -107,7 +107,7 @@ class TurtleSerializer2(RecursiveSerializer):
         self.base = None
 
     def preprocessTriple(self, triple):
-        super(TurtleSerializer2, self).preprocessTriple(triple)
+        super(LongTurtleSerializer, self).preprocessTriple(triple)
         for i, node in enumerate(triple):
             if node in self.keywords:
                 continue
@@ -123,12 +123,9 @@ class TurtleSerializer2(RecursiveSerializer):
         if not isinstance(uri, URIRef):
             return None
 
-        parts = None
-
         try:
             parts = self.store.compute_qname(uri, generate=gen_prefix)
         except:
-
             # is the uri a namespace in itself?
             pfx = self.store.store.prefix(uri)
 
diff --git a/rdflib/plugins/serializers/nquads.py b/rdflib/plugins/serializers/nquads.py
index e76c747d..ce2d2f7c 100644
--- a/rdflib/plugins/serializers/nquads.py
+++ b/rdflib/plugins/serializers/nquads.py
@@ -25,12 +25,15 @@ class NQuadsSerializer(Serializer):
         stream: IO[bytes],
         base: Optional[str] = None,
         encoding: Optional[str] = None,
-        **args
+        **args,
     ):
         if base is not None:
             warnings.warn("NQuadsSerializer does not support base.")
         if encoding is not None and encoding.lower() != self.encoding.lower():
-            warnings.warn("NQuadsSerializer does not use custom encoding.")
+            warnings.warn(
+                "NQuadsSerializer does not use custom encoding."
+                + "Given encoding was: %s" % encoding
+            )
         encoding = self.encoding
         for context in self.store.contexts():
             for triple in context:
diff --git a/rdflib/plugins/serializers/nt.py b/rdflib/plugins/serializers/nt.py
index 467de461..7862528d 100644
--- a/rdflib/plugins/serializers/nt.py
+++ b/rdflib/plugins/serializers/nt.py
@@ -22,23 +22,25 @@ class NTSerializer(Serializer):
 
     def __init__(self, store: Graph):
         Serializer.__init__(self, store)
-        self.encoding = "ascii"  # n-triples are ascii encoded
 
     def serialize(
         self,
         stream: IO[bytes],
         base: Optional[str] = None,
-        encoding: Optional[str] = None,
-        **args
+        encoding: Optional[str] = "utf-8",
+        **args,
     ):
         if base is not None:
             warnings.warn("NTSerializer does not support base.")
-        if encoding is not None and encoding.lower() != self.encoding.lower():
-            warnings.warn("NTSerializer does not use custom encoding.")
-        encoding = self.encoding
+        if encoding != "utf-8":
+            warnings.warn(
+                "NTSerializer always uses UTF-8 encoding."
+                + "Given encoding was: %s" % encoding
+            )
+
         for triple in self.store:
-            stream.write(_nt_row(triple).encode(self.encoding, "_rdflib_nt_escape"))
-        stream.write("\n".encode("latin-1"))
+            stream.write(_nt_row(triple).encode())
+        stream.write("\n".encode())
 
 
 class NT11Serializer(NTSerializer):
diff --git a/rdflib/plugins/serializers/rdfxml.py b/rdflib/plugins/serializers/rdfxml.py
index 901d911d..790c2393 100644
--- a/rdflib/plugins/serializers/rdfxml.py
+++ b/rdflib/plugins/serializers/rdfxml.py
@@ -1,4 +1,4 @@
-from typing import IO, Dict, Optional, Set, cast
+from typing import IO, Dict, Optional, Set
 from rdflib.plugins.serializers.xmlwriter import XMLWriter
 
 from rdflib.namespace import Namespace, RDF, RDFS  # , split_uri
@@ -46,7 +46,7 @@ class XMLSerializer(Serializer):
         stream: IO[bytes],
         base: Optional[str] = None,
         encoding: Optional[str] = None,
-        **args
+        **args,
     ):
         # if base is given here, use that, if not and a base is set for the graph use that
         if base is not None:
@@ -171,7 +171,7 @@ class PrettyXMLSerializer(Serializer):
         stream: IO[bytes],
         base: Optional[str] = None,
         encoding: Optional[str] = None,
-        **args
+        **args,
     ):
         self.__serialized: Dict[Identifier, int] = {}
         store = self.store
diff --git a/rdflib/plugins/serializers/trig.py b/rdflib/plugins/serializers/trig.py
index 5a606e40..3aa9ca68 100644
--- a/rdflib/plugins/serializers/trig.py
+++ b/rdflib/plugins/serializers/trig.py
@@ -60,7 +60,7 @@ class TrigSerializer(TurtleSerializer):
         base: Optional[str] = None,
         encoding: Optional[str] = None,
         spacious: Optional[bool] = None,
-        **args
+        **args,
     ):
         self.reset()
         self.stream = stream
diff --git a/rdflib/plugins/serializers/trix.py b/rdflib/plugins/serializers/trix.py
index 1612d815..63d58c44 100644
--- a/rdflib/plugins/serializers/trix.py
+++ b/rdflib/plugins/serializers/trix.py
@@ -28,7 +28,7 @@ class TriXSerializer(Serializer):
         stream: IO[bytes],
         base: Optional[str] = None,
         encoding: Optional[str] = None,
-        **args
+        **args,
     ):
 
         nm = self.store.namespace_manager
diff --git a/rdflib/plugins/serializers/xmlwriter.py b/rdflib/plugins/serializers/xmlwriter.py
index b0f1a06e..99d1e767 100644
--- a/rdflib/plugins/serializers/xmlwriter.py
+++ b/rdflib/plugins/serializers/xmlwriter.py
@@ -100,8 +100,8 @@ class XMLWriter(object):
         for pre, ns in self.extra_ns.items():
             if uri.startswith(ns):
                 if pre != "":
-                    return ":".join(pre, uri[len(ns) :])
+                    return ":".join(pre, uri[len(ns):])
                 else:
-                    return uri[len(ns) :]
+                    return uri[len(ns):]
 
         return self.nm.qname_strict(uri)
diff --git a/rdflib/query.py b/rdflib/query.py
index 0bc84284..dd911708 100644
--- a/rdflib/query.py
+++ b/rdflib/query.py
@@ -6,7 +6,7 @@ import warnings
 import types
 from typing import IO, TYPE_CHECKING, List, Optional, Union, cast
 
-from io import BytesIO, BufferedIOBase
+from io import BytesIO
 
 from urllib.parse import urlparse
 
@@ -333,7 +333,6 @@ class Result(object):
                 return self.vars == other.vars and self.bindings == other.bindings
             else:
                 return self.graph == other.graph
-
         except:
             return False
 
diff --git a/rdflib/serializer.py b/rdflib/serializer.py
index 74f29544..15a91d96 100644
--- a/rdflib/serializer.py
+++ b/rdflib/serializer.py
@@ -30,7 +30,7 @@ class Serializer:
         stream: IO[bytes],
         base: Optional[str] = None,
         encoding: Optional[str] = None,
-        **args
+        **args,
     ) -> None:
         """Abstract method"""
 
diff --git a/rdflib/tools/rdf2dot.py b/rdflib/tools/rdf2dot.py
index b6bed525..afaabd31 100644
--- a/rdflib/tools/rdf2dot.py
+++ b/rdflib/tools/rdf2dot.py
@@ -94,12 +94,10 @@ def rdf2dot(g, stream, opts={}):
         return nodes[x]
 
     def label(x, g):
-
         for labelProp in LABEL_PROPERTIES:
-            l = g.value(x, labelProp)
-            if l:
-                return l
-
+            l_ = g.value(x, labelProp)
+            if l_:
+                return l_
         try:
             return g.namespace_manager.compute_qname(x)[2]
         except:
diff --git a/test/n3/n3-writer-test-29.n3 b/test/n3/n3-writer-test-29.n3
index 86cf56e7..b6590cbd 100644
--- a/test/n3/n3-writer-test-29.n3
+++ b/test/n3/n3-writer-test-29.n3
@@ -1,23 +1,23 @@
-# Test qname-ization

-

-@prefix :       <http://example.org/here#> .

-@prefix ns:     <http://example.org/ns#> .

-@prefix ns2:    <http://example.org/ns/> .

-@prefix ex:     <http://example.org/> .

-

-# Ensure we don't write ns:p1/p2 (illegal URI)

-:x <http://example.org/ns/p1/p2> "1" .

-

-# Legal URI

-:x <http://example.org/ns#_1> "1" .

-

-# Numeric namespace prefix: gives a warning on reading

-# as Jena models work on XML rules.

-#@prefix 1:      <http://example.org/1#> .

-:x <http://example.org/1#1> "1" .

-

-# Numberic localname is allowed.

-:x ex:1 "2" .

-

-# As is _1

-:x ex:_1 "rdf:_1 test" .

+# Test qname-ization
+
+@prefix :       <http://example.org/here#> .
+@prefix ns:     <http://example.org/ns#> .
+@prefix ns2:    <http://example.org/ns/> .
+@prefix ex:     <http://example.org/> .
+
+# Ensure we don't write ns:p1/p2 (illegal URI)
+:x <http://example.org/ns/p1/p2> "1" .
+
+# Legal URI
+:x <http://example.org/ns#_1> "1" .
+
+# Numeric namespace prefix: gives a warning on reading
+# as Jena models work on XML rules.
+#@prefix 1:      <http://example.org/1#> .
+:x <http://example.org/1#1> "1" .
+
+# Numeric localname is allowed.
+:x ex:1 "2" .
+
+# As is _1
+:x ex:_1 "rdf:_1 test" .
diff --git a/test/n3/strquot.n3 b/test/n3/strquot.n3
index c421c11f..13da792e 100644
--- a/test/n3/strquot.n3
+++ b/test/n3/strquot.n3
@@ -1,5 +1,5 @@
-    @prefix : <#> .
-    
+@prefix : <#> .
+
     <>     <http://purl.org/dc/elements/1.1/description> """testing string parsing in N3.
 Hmm... how much of this is in the primer?
 How much should be there?
@@ -9,14 +9,14 @@ in python is sufficiently deployed
 nor does pythonwin on TimBL's laptop).
 
 """ .
-    
+
     :martin     :familyName "D\u00FCrst" .
-    
+
     :x     :prop "simple string" .
-    
+
     :y     :prop """triple quoted
 string with newlines in it.""" .
-    
+
     :z     :prop """string with " escaped quote marks""" .
 
    :zz     :escapes "\\\"\a\b\f\r\t\v" .
diff --git a/test/test_n3_suite.py b/test/test_n3_suite.py
index b4a96abb..a294d2bc 100644
--- a/test/test_n3_suite.py
+++ b/test/test_n3_suite.py
@@ -1,5 +1,4 @@
 import os
-import sys
 import logging
 
 import pytest
diff --git a/test/test_nt_misc.py b/test/test_nt_misc.py
index a9079859..71077487 100644
--- a/test/test_nt_misc.py
+++ b/test/test_nt_misc.py
@@ -33,15 +33,15 @@ class NTTestCase(unittest.TestCase):
     def testIssue78(self):
         g = Graph()
         g.add((URIRef("foo"), URIRef("foo"), Literal("R\u00E4ksm\u00F6rg\u00E5s")))
-        s = g.serialize(format="nt", encoding="latin-1")
-        self.assertEqual(type(s), bytes)
-        self.assertTrue(r"R\u00E4ksm\u00F6rg\u00E5s".encode("latin-1") in s)
+        s = g.serialize(format="nt")
+        self.assertEqual(type(s), str)
+        self.assertTrue("R\u00E4ksm\u00F6rg\u00E5s" in s)
 
     def testIssue146(self):
         g = Graph()
         g.add((URIRef("foo"), URIRef("foo"), Literal("test\n", lang="en")))
-        s = g.serialize(format="nt", encoding="latin-1").strip()
-        self.assertEqual(s, b'<foo> <foo> "test\\n"@en .')
+        s = g.serialize(format="nt").strip()
+        self.assertEqual(s, '<foo> <foo> "test\\n"@en .')
 
     def testIssue1144_rdflib(self):
         fname = "test/nt/lists-02.nt"
diff --git a/test/test_parser_hext.py b/test/test_parser_hext.py
new file mode 100644
index 00000000..3253922f
--- /dev/null
+++ b/test/test_parser_hext.py
@@ -0,0 +1,114 @@
+import sys
+from pathlib import Path
+sys.path.append(str(Path(__file__).parent.parent.absolute()))
+from rdflib import Dataset, ConjunctiveGraph, Literal
+from rdflib.namespace import XSD
+
+
+def test_small_string():
+    s = """
+        ["http://example.com/s01", "http://example.com/a", "http://example.com/Type1", "globalId", "", ""]
+        ["http://example.com/s01", "http://example.com/label", "This is a Label", "http://www.w3.org/1999/02/22-rdf-syntax-ns#langString", "en", ""]
+        ["http://example.com/s01", "http://example.com/comment", "This is a comment", "http://www.w3.org/2001/XMLSchema#string", "", ""]
+        ["http://example.com/s01", "http://example.com/creationDate", "2021-12-01", "http://www.w3.org/2001/XMLSchema#date", "", ""]
+        ["http://example.com/s01", "http://example.com/creationTime", "2021-12-01T12:13:00", "http://www.w3.org/2001/XMLSchema#dateTime", "", ""]
+        ["http://example.com/s01", "http://example.com/age", "42", "http://www.w3.org/2001/XMLSchema#integer", "", ""]
+        ["http://example.com/s01", "http://example.com/trueFalse", "false", ",http://www.w3.org/2001/XMLSchema#boolean", "", ""]
+        ["http://example.com/s01", "http://example.com/op1", "http://example.com/o1", "globalId", "", ""]
+        ["http://example.com/s01", "http://example.com/op1", "http://example.com/o2", "globalId", "", ""]
+        ["http://example.com/s01", "http://example.com/op2", "http://example.com/o3", "globalId", "", ""]
+        """
+    d = Dataset().parse(data=s, format="hext")
+    assert len(d) == 10
+
+
+def test_small_file_singlegraph():
+    d = Dataset().parse(Path(__file__).parent / "test_parser_hext_singlegraph.ndjson", format="hext")
+    assert len(d) == 10
+
+
+def test_small_file_multigraph():
+    d = ConjunctiveGraph()
+    assert len(d) == 0
+    d.parse(
+        Path(__file__).parent / "test_parser_hext_multigraph.ndjson",
+        format="hext",
+        publicID=d.default_context.identifier
+    )
+
+    """There are 22 lines in the file test_parser_hext_multigraph.ndjson. When loaded
+    into a Dataset, we get only 18 quads since the the dataset can contextualise
+    the triples and thus deduplicate 4."""
+    total_triples = 0
+    # count all the triples in the Dataset
+    for context in d.contexts():
+        for triple in context.triples((None, None, None)):
+            total_triples += 1
+    assert total_triples == 18
+
+
+def test_roundtrip():
+    # these are some RDF files that HexT can round-trip since the have no
+    # literals with no datatype declared:
+    TEST_DIR = Path(__file__).parent.absolute() / "nt"
+    files_to_skip = {
+        "paths-04.nt": "subject literal",
+        "even_more_literals.nt": "JSON decoding error",
+        "literals-02.nt": "JSON decoding error",
+        "more_literals.nt": "JSON decoding error",
+        "test.ntriples": "JSON decoding error",
+        "literals-05.nt": "JSON decoding error",
+        "i18n-01.nt": "JSON decoding error",
+        "literals-04.nt": "JSON decoding error",
+        "rdflibtest01.nt": "JSON decoding error",
+        "rdflibtest05.nt": "JSON decoding error",
+    }
+    tests = 0
+    skipped = 0
+    skip = False
+    print()
+    p = TEST_DIR.glob("**/*")
+    for f in [x for x in p if x.is_file()]:
+        tests += 1
+        print(f"Test {tests}: {f}")
+        if f.name not in files_to_skip.keys():
+            try:
+                cg = ConjunctiveGraph().parse(f, format="nt")
+                # print(cg.serialize(format="n3"))
+            except:
+                print(f"Skipping: could not NT parse")
+                skipped += 1
+                skip = True
+            if not skip:
+                cg2 = ConjunctiveGraph()
+                cg2.parse(
+                    data=cg.serialize(format="hext"),
+                    format="hext",
+                    publicID=cg2.default_context.identifier
+                )
+                if cg2.context_aware:
+                    for context in cg2.contexts():
+                        for triple in context.triples((None, None, None)):
+                            if type(triple[2]) == Literal:
+                                if triple[2].datatype == XSD.string:
+                                    context.remove((triple[0], triple[1], triple[2]))
+                                    context.add((triple[0], triple[1], Literal(str(triple[2]))))
+                else:
+                    for triple in cg2.triples((None, None, None)):
+                        if type(triple[2]) == Literal:
+                            if triple[2].datatype == XSD.string:
+                                cg2.remove((triple[0], triple[1], triple[2]))
+                                cg2.add((triple[0], triple[1], Literal(str(triple[2]))))
+
+                # print(cg2.serialize(format="trig"))
+                assert cg.isomorphic(cg2)
+            skip = False
+        else:
+            print(f"Skipping: {files_to_skip[f.name]}")
+
+    print(f"No. tests: {tests}")
+    print(f"No. tests skipped: {skipped}")
+
+
+if __name__ == "__main__":
+    test_small_file_multigraph()
diff --git a/test/test_parser_hext_multigraph.ndjson b/test/test_parser_hext_multigraph.ndjson
new file mode 100644
index 00000000..45d086e0
--- /dev/null
+++ b/test/test_parser_hext_multigraph.ndjson
@@ -0,0 +1,22 @@
+["_:n4d7dd184c5824f35aa064f17bd5d1440b1", "http://www.w3.org/1999/02/22-rdf-syntax-ns#type", "http://www.w3.org/2002/07/owl#Thing", "globalId", "", "http://example.com/g1"]
+["_:n4d7dd184c5824f35aa064f17bd5d1440b1", "http://www.w3.org/1999/02/22-rdf-syntax-ns#value", "thingy", "http://www.w3.org/2001/XMLSchema#string", "", "http://example.com/g1"]
+["http://example.com/s1", "http://example.com/p1", "http://example.com/o1", "globalId", "", ""]
+["http://example.com/s1", "http://example.com/p1", "http://example.com/o1", "globalId", "", ""]
+["http://example.com/s1", "http://example.com/p1", "http://example.com/o1", "globalId", "", "http://example.com/g1"]
+["http://example.com/s1", "http://example.com/p1", "http://example.com/o1", "globalId", "", "http://example.com/g2"]
+["http://example.com/s1", "http://example.com/p1", "http://example.com/o2", "globalId", "", ""]
+["http://example.com/s1", "http://example.com/p1", "http://example.com/o2", "globalId", "", ""]
+["http://example.com/s1", "http://example.com/p1", "http://example.com/o2", "globalId", "", "http://example.com/g1"]
+["http://example.com/s1", "http://example.com/p1", "http://example.com/o2", "globalId", "", "http://example.com/g2"]
+["http://example.com/s1", "http://example.com/p2", "_:n4d7dd184c5824f35aa064f17bd5d1440b1", "localId", "", "http://example.com/g1"]
+["http://example.com/s1", "http://example.com/p3", "Object 3", "http://www.w3.org/2001/XMLSchema#string", "", "http://example.com/g1"]
+["http://example.com/s1", "http://example.com/p3", "Object 4 - English", "http://www.w3.org/1999/02/22-rdf-syntax-ns#langString", "en", "http://example.com/g1"]
+["http://example.com/s1", "http://example.com/p4", "2021-12-03", "http://www.w3.org/2001/XMLSchema#date", "", "http://example.com/g1"]
+["http://example.com/s1", "http://example.com/p5", "42", "http://www.w3.org/2001/XMLSchema#integer", "", "http://example.com/g1"]
+["http://example.com/s1", "http://example.com/p6", "42", "http://www.w3.org/2001/XMLSchema#string", "", "http://example.com/g1"]
+["http://example.com/s11", "http://example.com/p11", "http://example.com/o11", "globalId", "", "http://example.com/g2"]
+["http://example.com/s11", "http://example.com/p11", "http://example.com/o12", "globalId", "", "http://example.com/g2"]
+["http://example.com/s21", "http://example.com/p21", "http://example.com/o21", "globalId", "", ""]
+["http://example.com/s21", "http://example.com/p21", "http://example.com/o21", "globalId", "", ""]
+["http://example.com/s21", "http://example.com/p21", "http://example.com/o22", "globalId", "", ""]
+["http://example.com/s21", "http://example.com/p21", "http://example.com/o22", "globalId", "", ""]
diff --git a/test/test_parser_hext_singlegraph.ndjson b/test/test_parser_hext_singlegraph.ndjson
new file mode 100644
index 00000000..bde2774d
--- /dev/null
+++ b/test/test_parser_hext_singlegraph.ndjson
@@ -0,0 +1,10 @@
+["http://example.com/s01", "http://example.com/a", "http://example.com/Type1", "globalId", "", ""]
+["http://example.com/s01", "http://example.com/label", "This is a Label", "http://www.w3.org/1999/02/22-rdf-syntax-ns#langString", "en", ""]
+["http://example.com/s01", "http://example.com/comment", "This is a comment", "http://www.w3.org/2001/XMLSchema#string", "", ""]
+["http://example.com/s01", "http://example.com/creationDate", "2021-12-01", "http://www.w3.org/2001/XMLSchema#date", "", ""]
+["http://example.com/s01", "http://example.com/creationTime", "2021-12-01T12:13:00", "http://www.w3.org/2001/XMLSchema#dateTime", "", ""]
+["http://example.com/s01", "http://example.com/age", "42", "http://www.w3.org/2001/XMLSchema#integer", "", ""]
+["http://example.com/s01", "http://example.com/trueFalse", "false", ",http://www.w3.org/2001/XMLSchema#boolean", "", ""]
+["http://example.com/s01", "http://example.com/op1", "http://example.com/o1", "globalId", "", ""]
+["http://example.com/s01", "http://example.com/op1", "http://example.com/o2", "globalId", "", ""]
+["http://example.com/s01", "http://example.com/op2", "http://example.com/o3", "globalId", "", ""]
diff --git a/test/test_prefixTypes.py b/test/test_prefixTypes.py
index 045c6056..57408d4f 100644
--- a/test/test_prefixTypes.py
+++ b/test/test_prefixTypes.py
@@ -25,10 +25,9 @@ class PrefixTypesTest(unittest.TestCase):
     """
 
     def test(self):
-        s = graph.serialize(format="n3", encoding="latin-1")
-        print(s)
-        self.assertTrue(b"foaf:Document" in s)
-        self.assertTrue(b"xsd:date" in s)
+        s = graph.serialize(format="n3")
+        self.assertTrue("foaf:Document" in s)
+        self.assertTrue("xsd:date" in s)
 
 
 if __name__ == "__main__":
diff --git a/test/test_preflabel.py b/test/test_preflabel.py
index 77ecbcd3..39057d48 100644
--- a/test/test_preflabel.py
+++ b/test/test_preflabel.py
@@ -10,9 +10,9 @@ from rdflib import URIRef
 class TestPrefLabel(unittest.TestCase):
     def setUp(self):
         self.g = ConjunctiveGraph()
-        self.u = URIRef("http://example.com/foo")
-        self.g.add([self.u, RDFS.label, Literal("foo")])
-        self.g.add([self.u, RDFS.label, Literal("bar")])
+        self.u = URIRef("https://example.com/foo")
+        self.g.add((self.u, RDFS.label, Literal("foo")))
+        self.g.add((self.u, RDFS.label, Literal("bar")))
 
     def test_default_label_sorting(self):
         res = sorted(self.g.preferredLabel(self.u))
@@ -29,7 +29,7 @@ class TestPrefLabel(unittest.TestCase):
         self.assertEqual(res, tgt)
 
     def test_default_preflabel_sorting(self):
-        self.g.add([self.u, SKOS.prefLabel, Literal("bla")])
+        self.g.add((self.u, SKOS.prefLabel, Literal("bla")))
         res = self.g.preferredLabel(self.u)
         tgt = [
             (
@@ -40,8 +40,8 @@ class TestPrefLabel(unittest.TestCase):
         self.assertEqual(res, tgt)
 
     def test_preflabel_lang_sorting_no_lang_attr(self):
-        self.g.add([self.u, SKOS.prefLabel, Literal("bla")])
-        self.g.add([self.u, SKOS.prefLabel, Literal("blubb", lang="en")])
+        self.g.add((self.u, SKOS.prefLabel, Literal("bla")))
+        self.g.add((self.u, SKOS.prefLabel, Literal("blubb", lang="en")))
         res = sorted(self.g.preferredLabel(self.u))
         tgt = [
             (
@@ -57,8 +57,8 @@ class TestPrefLabel(unittest.TestCase):
         self.assertEqual(res, tgt)
 
     def test_preflabel_lang_sorting_empty_lang_attr(self):
-        self.g.add([self.u, SKOS.prefLabel, Literal("bla")])
-        self.g.add([self.u, SKOS.prefLabel, Literal("blubb", lang="en")])
+        self.g.add((self.u, SKOS.prefLabel, Literal("bla")))
+        self.g.add((self.u, SKOS.prefLabel, Literal("blubb", lang="en")))
         res = self.g.preferredLabel(self.u, lang="")
         tgt = [
             (
@@ -69,7 +69,7 @@ class TestPrefLabel(unittest.TestCase):
         self.assertEqual(res, tgt)
 
     def test_preflabel_lang_sorting_en_lang_attr(self):
-        self.g.add([self.u, SKOS.prefLabel, Literal("blubb", lang="en")])
+        self.g.add((self.u, SKOS.prefLabel, Literal("blubb", lang="en")))
         res = self.g.preferredLabel(self.u, lang="en")
         tgt = [
             (
diff --git a/test/test_rdfxml.py b/test/test_rdfxml.py
index b0b222dc..e695355c 100644
--- a/test/test_rdfxml.py
+++ b/test/test_rdfxml.py
@@ -84,7 +84,7 @@ RDFCOREBASE = "http://www.w3.org/2000/10/rdf-tests/rdfcore/"
 
 
 def relative(url):
-    return url[len(RDFCOREBASE) :]
+    return url[len(RDFCOREBASE):]
 
 
 def resolve(rel):
diff --git a/test/test_roundtrip.py b/test/test_roundtrip.py
index f076e576..ec03a54d 100644
--- a/test/test_roundtrip.py
+++ b/test/test_roundtrip.py
@@ -5,17 +5,16 @@ import rdflib.compare
 
 try:
     from .test_nt_suite import all_nt_files
-
     assert all_nt_files
-    from .test_n3_suite import all_n3_files
 
+    from .test_n3_suite import all_n3_files
     assert all_n3_files
 except:
     from test.test_nt_suite import all_nt_files
     from test.test_n3_suite import all_n3_files
 
 """
-Test round-tripping by all serializers/parser that are registerd.
+Test round-tripping by all serializers/parser that are registered.
 This means, you may test more than just core rdflib!
 
 run with no arguments to test all formats + all files
@@ -27,17 +26,22 @@ python test/test_roundtrip.py xml nt test/nt/literals-02.nt
 
 tests roundtripping through rdf/xml with only the literals-02 file
 
+HexTuples format, "hext", cannot be used in all roundtrips due to its
+addition of xsd:string to literals of no declared type as this breaks
+(rdflib) graph isomorphism, and given that its JSON serialization is
+simple (lacking), so hext has been excluded from roundtripping here
+but provides some roundtrip test functions of its own (see test_parser_hext.py
+& test_serializer_hext.py)
+
 """
 
 
 SKIP = [
-    (
-        "xml",
-        "test/n3/n3-writer-test-29.n3",
-    ),  # has predicates that cannot be shortened to strict qnames
+    ("xml", "test/n3/n3-writer-test-29.n3"),
+    # has predicates that cannot be shortened to strict qnames
     ("xml", "test/nt/qname-02.nt"),  # uses a property that cannot be qname'd
-    ("trix", "test/n3/strquot.n3"),  # contains charachters forbidden by the xml spec
-    ("xml", "test/n3/strquot.n3"),  # contains charachters forbidden by the xml spec
+    ("trix", "test/n3/strquot.n3"),  # contains characters forbidden by the xml spec
+    ("xml", "test/n3/strquot.n3"),  # contains characters forbidden by the xml spec
     ("json-ld", "test/nt/keywords-04.nt"),  # known NT->JSONLD problem
     ("json-ld", "test/n3/example-misc.n3"),  # known N3->JSONLD problem
     ("json-ld", "test/n3/n3-writer-test-16.n3"),  # known N3->JSONLD problem
@@ -98,11 +102,12 @@ def get_cases():
         formats = parsers.intersection(serializers)
 
     for testfmt in formats:
-        if "/" in testfmt:
-            continue  # skip double testing
-        for f, infmt in all_nt_files():
-            if (testfmt, f) not in SKIP:
-                yield roundtrip, (infmt, testfmt, f)
+        if testfmt != "hext":
+            if "/" in testfmt:
+                continue  # skip double testing
+            for f, infmt in all_nt_files():
+                if (testfmt, f) not in SKIP:
+                    yield roundtrip, (infmt, testfmt, f)
 
 
 @pytest.mark.parametrize("checker, args", get_cases())
@@ -120,13 +125,18 @@ def get_n3_test():
         formats = parsers.intersection(serializers)
 
     for testfmt in formats:
-        if "/" in testfmt:
-            continue  # skip double testing
-        for f, infmt in all_n3_files():
-            if (testfmt, f) not in SKIP:
-                yield roundtrip, (infmt, testfmt, f)
+        if testfmt != "hext":
+            if "/" in testfmt:
+                continue  # skip double testing
+            for f, infmt in all_n3_files():
+                if (testfmt, f) not in SKIP:
+                    yield roundtrip, (infmt, testfmt, f)
 
 
 @pytest.mark.parametrize("checker, args", get_n3_test())
 def test_n3(checker, args):
     checker(args)
+
+
+if __name__ == "__main__":
+    print("hi")
diff --git a/test/test_serialize.py b/test/test_serializer.py
index d3dfda57..d3dfda57 100644
--- a/test/test_serialize.py
+++ b/test/test_serializer.py
diff --git a/test/test_serializer_hext.py b/test/test_serializer_hext.py
new file mode 100644
index 00000000..c322a211
--- /dev/null
+++ b/test/test_serializer_hext.py
@@ -0,0 +1,223 @@
+import sys
+from pathlib import Path
+sys.path.append(str(Path(__file__).parent.parent.absolute()))
+from rdflib import Dataset, Graph
+import json
+
+
+def test_hext_graph():
+    """Tests single-grant (not context-aware) data"""
+    g = Graph()
+    turtle_data = """
+            PREFIX ex: <http://example.com/>
+            PREFIX owl: <http://www.w3.org/2002/07/owl#>
+            PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
+            PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
+
+            ex:s1
+                ex:p1 ex:o1 , ex:o2 ;
+                ex:p2 [
+                    a owl:Thing ;
+                    rdf:value "thingy" ;
+                ] ;
+                ex:p3 "Object 3" , "Object 4 - English"@en ;
+                ex:p4 "2021-12-03"^^xsd:date ;
+                ex:p5 42 ;
+                ex:p6 "42" ;
+                ex:p7 true ;
+                ex:p8 "false"^^xsd:boolean ;
+            .
+            """
+
+    g.parse(data=turtle_data, format="turtle")
+    out = g.serialize(format="hext")
+    # note: cant' test for BNs in result as they will be different ever time
+    testing_lines = [
+        [False, '["http://example.com/s1", "http://example.com/p1", "http://example.com/o2", "globalId", "", ""]'],
+        [False, '["http://example.com/s1", "http://example.com/p3", "Object 3", "http://www.w3.org/2001/XMLSchema#string", "", ""]'],
+        [False, '["http://example.com/s1", "http://example.com/p3", "Object 4 - English", "http://www.w3.org/1999/02/22-rdf-syntax-ns#langString", "en", ""]'],
+        [False, '["http://example.com/s1", "http://example.com/p1", "http://example.com/o1", "globalId", "", ""]'],
+        [False, '["http://example.com/s1", "http://example.com/p4", "2021-12-03", "http://www.w3.org/2001/XMLSchema#date", "", ""]'],
+        [False, '["http://example.com/s1", "http://example.com/p6", "42", "http://www.w3.org/2001/XMLSchema#string", "", ""]'],
+        [False, '["http://example.com/s1", "http://example.com/p7", "true", "http://www.w3.org/2001/XMLSchema#boolean", "", ""]'],
+        [False, '"http://www.w3.org/1999/02/22-rdf-syntax-ns#value", "thingy", "http://www.w3.org/2001/XMLSchema#string", "", ""]'],
+        [False, '["http://example.com/s1", "http://example.com/p2"'],
+        [False, '["http://example.com/s1", "http://example.com/p5", "42", "http://www.w3.org/2001/XMLSchema#integer", "", ""]'],
+        [False, '"http://www.w3.org/1999/02/22-rdf-syntax-ns#type", "http://www.w3.org/2002/07/owl#Thing", "globalId", "", ""]'],
+        [False, '["http://example.com/s1", "http://example.com/p8", "false", "http://www.w3.org/2001/XMLSchema#boolean", "", ""]'],
+    ]
+    for line in out.splitlines():
+        for test in testing_lines:
+            if test[1] in line:
+                test[0] = True
+
+    assert all([x[0] for x in testing_lines])
+
+
+def test_hext_dataset():
+    """Tests context-aware (multigraph) data"""
+    d = Dataset()
+    trig_data = """
+            PREFIX ex: <http://example.com/>
+            PREFIX owl: <http://www.w3.org/2002/07/owl#>
+            PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
+            PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
+
+            ex:g1 {
+                ex:s1
+                    ex:p1 ex:o1 , ex:o2 ;
+                    ex:p2 [
+                        a owl:Thing ;
+                        rdf:value "thingy" ;
+                    ] ;
+                    ex:p3 "Object 3" , "Object 4 - English"@en ;
+                    ex:p4 "2021-12-03"^^xsd:date ;
+                    ex:p5 42 ;
+                    ex:p6 "42" ;
+                .
+            }
+
+            ex:g2 {
+                ex:s1
+                    ex:p1 ex:o1 , ex:o2 ;
+                .
+                ex:s11 ex:p11 ex:o11 , ex:o12 .
+            }
+
+            # default graph triples
+            ex:s1 ex:p1 ex:o1 , ex:o2 .
+            ex:s21 ex:p21 ex:o21 , ex:o22 .
+           """
+    d.parse(data=trig_data, format="trig", publicID=d.default_context.identifier)
+    out = d.serialize(format="hext")
+    # note: cant' test for BNs in result as they will be different ever time
+    testing_lines = [
+        [False, '["http://example.com/s21", "http://example.com/p21", "http://example.com/o21", "globalId", "", ""]'],
+        [False, '["http://example.com/s21", "http://example.com/p21", "http://example.com/o22", "globalId", "", ""]'],
+        [False, '["http://example.com/s1", "http://example.com/p1", "http://example.com/o2", "globalId", "", ""]'],
+        [False, '["http://example.com/s1", "http://example.com/p1", "http://example.com/o1", "globalId", "", ""]'],
+        [False, '["http://example.com/s11", "http://example.com/p11", "http://example.com/o12", "globalId", "", "http://example.com/g2"]'],
+        [False, '["http://example.com/s1", "http://example.com/p1", "http://example.com/o2", "globalId", "", "http://example.com/g2"]'],
+        [False, '["http://example.com/s11", "http://example.com/p11", "http://example.com/o11", "globalId", "", "http://example.com/g2"]'],
+        [False, '["http://example.com/s1", "http://example.com/p1", "http://example.com/o1", "globalId", "", "http://example.com/g2"]'],
+        [False, '["http://example.com/s1", "http://example.com/p1", "http://example.com/o2", "globalId", "", "http://example.com/g1"]'],
+        [False, '["http://example.com/s1", "http://example.com/p2"'],
+        [False, '"http://www.w3.org/1999/02/22-rdf-syntax-ns#value", "thingy", "http://www.w3.org/2001/XMLSchema#string", "", "http://example.com/g1"]'],
+        [False, '"http://www.w3.org/1999/02/22-rdf-syntax-ns#type", "http://www.w3.org/2002/07/owl#Thing", "globalId", "", "http://example.com/g1"]'],
+        [False, '["http://example.com/s1", "http://example.com/p3", "Object 4 - English", "http://www.w3.org/1999/02/22-rdf-syntax-ns#langString", "en", "http://example.com/g1"]'],
+        [False, '["http://example.com/s1", "http://example.com/p6", "42", "http://www.w3.org/2001/XMLSchema#string", "", "http://example.com/g1"]'],
+        [False, '["http://example.com/s1", "http://example.com/p4", "2021-12-03", "http://www.w3.org/2001/XMLSchema#date", "", "http://example.com/g1"]'],
+        [False, '["http://example.com/s1", "http://example.com/p1", "http://example.com/o1", "globalId", "", "http://example.com/g1"]'],
+        [False, '["http://example.com/s1", "http://example.com/p5", "42", "http://www.w3.org/2001/XMLSchema#integer", "", "http://example.com/g1"]'],
+        [False, '["http://example.com/s1", "http://example.com/p3", "Object 3", "http://www.w3.org/2001/XMLSchema#string", "", "http://example.com/g1"]'],
+    ]
+    for line in out.splitlines():
+        for test in testing_lines:
+            if test[1] in line:
+                test[0] = True
+
+    assert all([x[0] for x in testing_lines])
+
+
+def test_hext_json_representation():
+    """Tests to see if every link in the ND-JSON Hextuple result is, in fact, JSON"""
+    d = Dataset()
+    trig_data = """
+            PREFIX ex: <http://example.com/>
+            PREFIX owl: <http://www.w3.org/2002/07/owl#>
+            PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
+            PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
+
+            ex:g1 {
+                ex:s1
+                    ex:p1 ex:o1 , ex:o2 ;
+                    ex:p2 [
+                        a owl:Thing ;
+                        rdf:value "thingy" ;
+                    ] ;
+                    ex:p3 "Object 3" , "Object 4 - English"@en ;
+                    ex:p4 "2021-12-03"^^xsd:date ;
+                    ex:p5 42 ;
+                    ex:p6 "42" ;
+                .
+            }
+
+            ex:g2 {
+                ex:s1
+                    ex:p1 ex:o1 , ex:o2 ;
+                .
+                ex:s11 ex:p11 ex:o11 , ex:o12 .
+            }
+
+            # default graph triples
+            ex:s1 ex:p1 ex:o1 , ex:o2 .
+            ex:s21 ex:p21 ex:o21 , ex:o22 .
+           """
+    d.parse(data=trig_data, format="trig")
+    out = d.serialize(format="hext")
+    for line in out.splitlines():
+        j = json.loads(line)
+        assert isinstance(j, list)
+
+
+def test_hext_dataset_linecount():
+    d = Dataset()
+    assert len(d) == 0
+    d.parse(
+        Path(__file__).parent / "test_parser_hext_multigraph.ndjson",
+        format="hext",
+        publicID=d.default_context.identifier
+    )
+    total_triples = 0
+    # count all the triples in the Dataset
+    for context in d.contexts():
+        for triple in context.triples((None, None, None)):
+            total_triples += 1
+    assert total_triples == 18
+
+    # count the number of serialized Hextuples, should be 22, as per the original file
+    lc = len(d.serialize(format="hext").splitlines())
+    assert lc == 22
+
+
+def test_roundtrip():
+    d = Dataset()
+    d.parse(
+        Path(__file__).parent / "test_parser_hext_multigraph.ndjson",
+        format="hext",
+        publicID=d.default_context.identifier
+    )
+    d.default_union = True
+    with open(str(Path(__file__).parent / "test_parser_hext_multigraph.ndjson")) as i:
+        ordered_input = "".join(sorted(i.readlines())).strip()
+
+    ordered_output = "\n".join(sorted(d.serialize(format="hext").split("\n"))).strip()
+
+    assert ordered_output == ordered_input
+
+
+# def _make_large_graph():
+#     import random
+#
+#     EX = Namespace("http://example.com/")
+#     g = Graph()
+#
+#     for i in range(1000):
+#         s = EX["s" + str(random.randint(1, 10000)).zfill(5)]
+#         p = EX["p" + str(random.randint(1, 10000)).zfill(5)]
+#         o_r = random.randint(1, 10000)
+#         if o_r > 5000:
+#             o = EX["p" + str(o_r).zfill(5)]
+#         else:
+#             o = Literal("p" + str(o_r).zfill(5))
+#         g.add((s, p, o))
+#     return g
+#
+#
+# def test_hext_scaling():
+#     g = _make_large_graph()
+#     g.serialize(destination="large.ndjson", format="hext")
+#
+#
+if __name__ == "__main__":
+    test_roundtrip()
diff --git a/test/test_turtle2.py b/test/test_serializer_longturtle.py
index fef0efab..cc184787 100644
--- a/test/test_turtle2.py
+++ b/test/test_serializer_longturtle.py
@@ -1,9 +1,9 @@
-# tests for the turtle2 serializer
+# tests for the longturtle Serializer
 
 from rdflib import Graph
 
 
-def test_turtle2():
+def test_longturtle():
     g = Graph()
 
     g.parse(
@@ -86,7 +86,7 @@ def test_turtle2():
         """,
         format="turtle",
     )
-    s = g.serialize(format="turtle2")
+    s = g.serialize(format="longturtle")
     lines = s.split("\n")
 
     assert "ex:b" in lines
diff --git a/test/test_trix_serialize.py b/test/test_serializer_trix.py
index d0824aa9..d0824aa9 100644
--- a/test/test_trix_serialize.py
+++ b/test/test_serializer_trix.py
diff --git a/test/test_turtle_serialize.py b/test/test_serializer_turtle.py
index b17492e0..b17492e0 100644
--- a/test/test_turtle_serialize.py
+++ b/test/test_serializer_turtle.py
diff --git a/test/test_serializexml.py b/test/test_serializer_xml.py
index 6ca25a92..6ca25a92 100644
--- a/test/test_serializexml.py
+++ b/test/test_serializer_xml.py
diff --git a/test/test_swap_n3.py b/test/test_swap_n3.py
index 1734806c..c0b596cd 100644
--- a/test/test_swap_n3.py
+++ b/test/test_swap_n3.py
@@ -1,6 +1,5 @@
 import os
 import sys
-import unittest
 
 import pytest
 
diff --git a/test/test_term.py b/test/test_term.py
index e154bd4e..0f9dbea2 100644
--- a/test/test_term.py
+++ b/test/test_term.py
@@ -74,16 +74,16 @@ class TestLiteral(unittest.TestCase):
             sorted(literals)
             orderable = True
         except TypeError as e:
-            for l in literals:
-                print(repr(l), repr(l.value))
+            for l_ in literals:
+                print(repr(l_), repr(l_.value))
             print(e)
             orderable = False
         self.assertTrue(orderable)
 
         # also make sure that within a datetime things are still ordered:
         l1 = [
-            Literal(l, datatype=XSD.dateTime)
-            for l in [
+            Literal(l_, datatype=XSD.dateTime)
+            for l_ in [
                 "2001-01-01T00:00:00",
                 "2001-01-01T01:00:00",
                 "2001-01-01T01:00:01",