add overload stubs for proxied classes

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### Description
Closes #1146
Closes #1147

<!-- Describe your changes in detail -->

Overloaded functions would not have type stubs generated by the stub generator for proxied classes. Now they will.

### Checklist
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This pull request is:

- [ ] A documentation / typographical error fix
	- Good to go, no issue or tests are needed
- [x] A short code fix
	- please include the issue number, and create an issue if none exists, which
	  must include a complete example of the issue.  one line code fixes without an
	  issue and demonstration will not be accepted.
	- Please include: `Fixes: #<issue number>` in the commit message
	- please include tests.   one line code fixes without tests will not be accepted.
- [ ] A new feature implementation
	- please include the issue number, and create an issue if none exists, which must
	  include a complete example of how the feature would look.
	- Please include: `Fixes: #<issue number>` in the commit message
	- please include tests.

Closes: #1148
Pull-request: https://github.com/sqlalchemy/alembic/pull/1148
Pull-request-sha: ed3c28cc78e57314b7a4e533d77108efc6751949

Change-Id: I7c0ee9d333015174ee6ab754909748f745af2ff9

3 files changed, 17 insertions, 7 deletions

diff --git a/alembic/context.pyi b/alembic/context.pyi
index 9871fad..86345c4 100644
--- a/alembic/context.pyi
+++ b/alembic/context.pyi
@@ -7,7 +7,9 @@ from typing import Callable
 from typing import ContextManager
 from typing import Dict
 from typing import List
+from typing import Literal
 from typing import Optional
+from typing import overload
 from typing import TextIO
 from typing import Tuple
 from typing import TYPE_CHECKING
@@ -644,8 +646,13 @@ def get_tag_argument() -> Optional[str]:
 
     """
 
+@overload
+def get_x_argument(as_dictionary: Literal[False]) -> List[str]: ...
+@overload
+def get_x_argument(as_dictionary: Literal[True]) -> Dict[str, str]: ...
+@overload
 def get_x_argument(
-    as_dictionary: bool = False,
+    as_dictionary: bool = ...,
 ) -> Union[List[str], Dict[str, str]]:
     """Return the value(s) passed for the ``-x`` argument, if any.
 
diff --git a/alembic/runtime/environment.py b/alembic/runtime/environment.py
index 44dcd72..a441d1f 100644
--- a/alembic/runtime/environment.py
+++ b/alembic/runtime/environment.py
@@ -269,15 +269,17 @@ class EnvironmentContext(util.ModuleClsProxy):
         return self.context_opts.get("tag", None)
 
     @overload
-    def get_x_argument(  # type:ignore[misc]
-        self, as_dictionary: Literal[False] = ...
-    ) -> List[str]:
+    def get_x_argument(self, as_dictionary: Literal[False]) -> List[str]:
         ...
 
     @overload
-    def get_x_argument(  # type:ignore[misc]
-        self, as_dictionary: Literal[True] = ...
-    ) -> Dict[str, str]:
+    def get_x_argument(self, as_dictionary: Literal[True]) -> Dict[str, str]:
+        ...
+
+    @overload
+    def get_x_argument(
+        self, as_dictionary: bool = ...
+    ) -> Union[List[str], Dict[str, str]]:
         ...
 
     def get_x_argument(
diff --git a/alembic/util/compat.py b/alembic/util/compat.py
index 289aaa2..2fe4957 100644
--- a/alembic/util/compat.py
+++ b/alembic/util/compat.py
@@ -10,6 +10,7 @@ from sqlalchemy.util.compat import inspect_formatargspec  # noqa
 
 is_posix = os.name == "posix"
 
+py311 = sys.version_info >= (3, 11)
 py39 = sys.version_info >= (3, 9)
 py38 = sys.version_info >= (3, 8)