diff --git a/xarray/core/dataarray.py b/xarray/core/dataarray.py
index 4a48cb2b3e9..c66794bc4c5 100644
--- a/xarray/core/dataarray.py
+++ b/xarray/core/dataarray.py
@@ -7252,11 +7252,9 @@ def resample(
         offset: pd.Timedelta | datetime.timedelta | str | None = None,
         origin: str | DatetimeLike = "start_day",
         restore_coord_dims: bool | None = None,
-        **indexer_kwargs: str
-        | datetime.timedelta
-        | pd.Timedelta
-        | pd.DateOffset
-        | Resampler,
+        **indexer_kwargs: (
+            str | datetime.timedelta | pd.Timedelta | pd.DateOffset | Resampler
+        ),
     ) -> DataArrayResample:
         """Returns a Resample object for performing resampling operations.
 
diff --git a/xarray/core/dataset.py b/xarray/core/dataset.py
index 63c53ed5768..24e311913ba 100644
--- a/xarray/core/dataset.py
+++ b/xarray/core/dataset.py
@@ -10693,11 +10693,9 @@ def resample(
         offset: pd.Timedelta | datetime.timedelta | str | None = None,
         origin: str | DatetimeLike = "start_day",
         restore_coord_dims: bool | None = None,
-        **indexer_kwargs: str
-        | datetime.timedelta
-        | pd.Timedelta
-        | pd.DateOffset
-        | Resampler,
+        **indexer_kwargs: (
+            str | datetime.timedelta | pd.Timedelta | pd.DateOffset | Resampler
+        ),
     ) -> DatasetResample:
         """Returns a Resample object for performing resampling operations.
 
diff --git a/xarray/core/resample_cftime.py b/xarray/core/resample_cftime.py
index 2c9b13151ab..983f31decc5 100644
--- a/xarray/core/resample_cftime.py
+++ b/xarray/core/resample_cftime.py
@@ -75,11 +75,9 @@ class CFTimeGrouper:
 
     def __init__(
         self,
-        freq: str
-        | datetime.timedelta
-        | pd.Timedelta
-        | pd.DateOffset
-        | BaseCFTimeOffset,
+        freq: (
+            str | datetime.timedelta | pd.Timedelta | pd.DateOffset | BaseCFTimeOffset
+        ),
         closed: SideOptions | None = None,
         label: SideOptions | None = None,
         origin: str | CFTimeDatetime = "start_day",