Guard typing_extension import (#10413)

Author: sjperkins

xarray/core/accessor_dt.py

@@ -5,7 +5,6 @@
 
 import numpy as np
 import pandas as pd
-from typing_extensions import Self
 
 from xarray.coding.calendar_ops import _decimal_year
 from xarray.coding.times import infer_calendar_name
@@ -21,12 +20,19 @@
 from xarray.namedarray.utils import is_duck_dask_array
 
 if TYPE_CHECKING:
+    import sys
+
     from numpy.typing import DTypeLike
 
     from xarray.core.dataarray import DataArray
     from xarray.core.dataset import Dataset
     from xarray.core.types import CFCalendar
 
+    if sys.version_info >= (3, 11):
+        from typing import Self
+    else:
+        from typing_extensions import Self
+
 
 def _season_from_months(months):
     """Compute season (DJF, MAM, JJA, SON) from month ordinal"""