first using notations

Author: anmyachev

pandas/_typing.py

@@ -4,8 +4,14 @@
 import numpy as np
 
 from pandas.core.dtypes.dtypes import ExtensionDtype
-from pandas.core.dtypes.generic import ABCExtensionArray
+from pandas.core.dtypes.generic import (
+    ABCExtensionArray, ABCIndexClass, ABCSeries)
+
+# using a certain style for notations (without ABC prefix)
+IndexLike = Union[ABCIndexClass]
+SeriesLike = Union[ABCSeries]
 
 ArrayLike = Union[ABCExtensionArray, np.ndarray]
 Dtype = Union[str, np.dtype, ExtensionDtype]
 FilePathOrBuffer = Union[str, Path, IO[AnyStr]]
+IndexLikeOrNdarray = Union[IndexLike, np.ndarray]

pandas/core/tools/datetimes.py

@@ -18,9 +18,16 @@
 from pandas.core.dtypes.generic import ABCDataFrame, ABCIndexClass, ABCSeries
 from pandas.core.dtypes.missing import notna
 
+from pandas._typing import (
+    ArrayLike, IndexLike, IndexLikeOrNdarray, SeriesLike, Union)
 from pandas.core import algorithms
 
 
+# notations
+IntFltStrDateLisTuplArrSer = Union[int, float, str, list, tuple,
+                                   datetime, ArrayLike, SeriesLike]
+
+
 def _guess_datetime_format_for_array(arr, **kwargs):
     # Try to guess the format based on the first non-NaN element
     non_nan_elements = notna(arr).nonzero()[0]
@@ -60,7 +67,7 @@ def _maybe_cache(arg, format, cache, convert_listlike):
     return cache_array
 
 
-def _box_as_indexlike(dt_array, tz=None, name=None):
+def _box_as_indexlike(dt_array: ArrayLike, tz=None, name=None) -> IndexLike:
     """
     Properly boxes the ndarray of datetimes to DatetimeIndex
     if it is possible or to generic Index instead
@@ -86,7 +93,9 @@ def _box_as_indexlike(dt_array, tz=None, name=None):
     return Index(dt_array, name=name)
 
 
-def _convert_and_box_cache(arg, cache_array, box, name=None):
+def _convert_and_box_cache(arg: IntFltStrDateLisTuplArrSer,
+                           cache_array: SeriesLike,
+                           box: bool, name=None) -> IndexLikeOrNdarray:
     """
     Convert array of dates with a cache and box the result