ENH: set __module__ on isna and notna

pandas/core/dtypes/missing.py

@@ -19,6 +19,7 @@
     NaT,
     iNaT,
 )
+from pandas.util._decorators import set_module
 
 from pandas.core.dtypes.common import (
     DT64NS_DTYPE,
@@ -93,6 +94,7 @@ def isna(
 def isna(obj: object) -> bool | npt.NDArray[np.bool_] | NDFrame: ...
 
 
+@set_module("pandas")
 def isna(obj: object) -> bool | npt.NDArray[np.bool_] | NDFrame:
     """
     Detect missing values for an array-like object.
@@ -307,6 +309,7 @@ def notna(
 def notna(obj: object) -> bool | npt.NDArray[np.bool_] | NDFrame: ...
 
 
+@set_module("pandas")
 def notna(obj: object) -> bool | npt.NDArray[np.bool_] | NDFrame:
     """
     Detect non-missing values for an array-like object.

pandas/tests/api/test_api.py

@@ -417,6 +417,8 @@ def test_set_module():
     assert pd.Period.__module__ == "pandas"
     assert pd.Timestamp.__module__ == "pandas"
     assert pd.Timedelta.__module__ == "pandas"
+    assert pd.isna.__module__ == "pandas"
+    assert pd.notna.__module__ == "pandas"
     assert pd.merge.__module__ == "pandas"
     assert pd.merge_ordered.__module__ == "pandas"
     assert pd.merge_asof.__module__ == "pandas"