Small improvements

docs/src/conf.py

@@ -246,6 +246,7 @@ def _dotv(version):
 # See https://www.sphinx-doc.org/en/master/usage/extensions/intersphinx.html
 intersphinx_mapping = {
     "cartopy": ("https://scitools.org.uk/cartopy/docs/latest/", None),
+    "cftime": ("https://unidata.github.io/cftime/", None),
     "dask": ("https://docs.dask.org/en/stable/", None),
     "iris-esmf-regrid": ("https://iris-esmf-regrid.readthedocs.io/en/stable/", None),
     "matplotlib": ("https://matplotlib.org/stable/", None),

lib/iris/coord_categorisation.py

@@ -51,7 +51,7 @@ def add_categorised_coord(
     category_function : callable
         Function(coordinate, value), returning a category value for a coordinate
         point-value. If ``value`` has a type hint :obj:`cftime.datetime`, the
-        coordinate points are translated to :obj:`cftime.datetime`s before
+        coordinate points are translated to :obj:`cftime.datetime` s before
         calling ``category_function``.
     units : str, default="1"
         Units of the category value, typically 'no_unit' or '1'.
@@ -434,8 +434,6 @@ def add_season_membership(cube, coord, season, name="season_membership"):
     months = _months_in_season(season)
 
     def _season_membership(_, value: cftime.datetime) -> bool:
-        if value.month in months:
-            return True
-        return False
+        return value.month in months
 
     add_categorised_coord(cube, name, coord, _season_membership)