pandas-dev#25790 Added TypeVar to hint in core/indexes/base.py

Author: gwrome

pandas/core/indexes/base.py

@@ -1,7 +1,7 @@
 from datetime import datetime, timedelta
 import operator
 from textwrap import dedent
-from typing import Union
+from typing import TypeVar, Union
 import warnings
 
 import numpy as np
@@ -164,6 +164,9 @@ def _new_Index(cls, d):
     return cls.__new__(cls, **d)
 
 
+INDEXTYPE = TypeVar('INDEXTYPE', bound='Index')
+
+
 class Index(IndexOpsMixin, PandasObject):
     """
     Immutable ndarray implementing an ordered, sliceable set. The basic object
@@ -3632,7 +3635,7 @@ def values(self):
         return self._data.view(np.ndarray)
 
     @property
-    def _values(self) -> Union[ExtensionArray, Index, np.ndarray]:
+    def _values(self) -> Union[ExtensionArray, INDEXTYPE, np.ndarray]:
         # TODO(EA): remove index types as they become extension arrays
         """
         The best array representation.