appease the typechecker

Author: wyattscarpenter

mypy/fastparse.py

@@ -151,19 +151,23 @@ def ast3_parse(
     #     Note that the functions in this module are only designed to parse syntactically valid Python code (code that does not raise when parsed using ast.parse()). The behavior of the functions in this module is **undefined** when providing invalid Python code and it can change at any point.
     # So, we cannot rely on roundtrip behavior in tokenize iff ast.parse would throw when given `source`.
     # The simplest way to deal with that is just to call ast.parse twice, once before and once after. So, we do that.
-    p = lambda: ast3.parse(
-        source, filename, mode, type_comments=True, feature_version=feature_version
-    )
+    def p() -> AST:
+        return ast3.parse(
+            source, filename, mode, type_comments=True, feature_version=feature_version
+        )
     p()  # Call to assure syntactic validity (will throw an exception otherwise, exiting this function).
     if isinstance(source, str):
         tokens = tokenize.generate_tokens(io.StringIO(source).readline)
         to_find, to_replace = r"#\s*mypy:\s*ignore(?![-_])", "# type: ignore"
+        source = tokenize.untokenize(
+            (t, re.sub(to_find, to_replace, s) if t == tokenize.COMMENT else s) for t, s, *_ in tokens
+        )
     else:
         tokens = tokenize.tokenize(io.BytesIO(source).readline)
         to_find, to_replace = rb"#\s*mypy:\s*ignore(?![-_])", b"# type: ignore"
-    source = tokenize.untokenize(
-        (t, re.sub(to_find, to_replace, s) if t == tokenize.COMMENT else s) for t, s, *_ in tokens
-    )
+        source = tokenize.untokenize(
+            (t, re.sub(to_find, to_replace, s) if t == tokenize.COMMENT else s) for t, s, *_ in tokens
+        )
     return p()