Typing of GroupBy & Co.

doc/whats-new.rst

@@ -22,6 +22,11 @@ v2022.06.0 (unreleased)
 New Features
 ~~~~~~~~~~~~
 
+- Initial typing support for :py:meth:`groupby`, :py:meth:`rolling`, :py:meth:`rolling_exp`,
+  :py:meth:`coarsen`, :py:meth:`weighted`, :py:meth:`resample`,
+  (:pull:`6702`)
+  By `Michael Niklas <https://github.com/headtr1ck>`_.
+
 
 Deprecations
 ~~~~~~~~~~~~

xarray/core/alignment.py

@@ -215,7 +215,7 @@ def _normalize_indexes(
         normalized_index_vars = {}
         for idx, index_vars in Indexes(xr_indexes, xr_variables).group_by_index():
             coord_names_and_dims = []
-            all_dims = set()
+            all_dims: set[Hashable] = set()
 
             for name, var in index_vars.items():
                 dims = var.dims