typed-ast: fix get_docstring, allow buffer (#9019)

stubs/typed-ast/typed_ast/ast27.pyi

@@ -1,3 +1,4 @@
+from _typeshed import ReadableBuffer
 from collections.abc import Iterator
 from typing import Any
 from typing_extensions import TypeAlias
@@ -9,11 +10,11 @@ class NodeVisitor:
 class NodeTransformer(NodeVisitor):
     def generic_visit(self, node: AST) -> None: ...
 
-def parse(source: str | bytes, filename: str | bytes = ..., mode: str = ...) -> AST: ...
+def parse(source: str | ReadableBuffer, filename: str | ReadableBuffer = ..., mode: str = ...) -> AST: ...
 def copy_location(new_node: AST, old_node: AST) -> AST: ...
 def dump(node: AST, annotate_fields: bool = ..., include_attributes: bool = ...) -> str: ...
 def fix_missing_locations(node: AST) -> AST: ...
-def get_docstring(node: AST, clean: bool = ...) -> bytes | None: ...
+def get_docstring(node: AST, clean: bool = ...) -> str | bytes | None: ...
 def increment_lineno(node: AST, n: int = ...) -> AST: ...
 def iter_child_nodes(node: AST) -> Iterator[AST]: ...
 def iter_fields(node: AST) -> Iterator[tuple[str, Any]]: ...

stubs/typed-ast/typed_ast/ast3.pyi

@@ -1,3 +1,4 @@
+from _typeshed import ReadableBuffer
 from collections.abc import Iterator
 from typing import Any
 from typing_extensions import TypeAlias
@@ -9,7 +10,9 @@ class NodeVisitor:
 class NodeTransformer(NodeVisitor):
     def generic_visit(self, node: AST) -> None: ...
 
-def parse(source: str | bytes, filename: str | bytes = ..., mode: str = ..., feature_version: int = ...) -> AST: ...
+def parse(
+    source: str | ReadableBuffer, filename: str | ReadableBuffer = ..., mode: str = ..., feature_version: int = ...
+) -> AST: ...
 def copy_location(new_node: AST, old_node: AST) -> AST: ...
 def dump(node: AST, annotate_fields: bool = ..., include_attributes: bool = ...) -> str: ...
 def fix_missing_locations(node: AST) -> AST: ...