FIX: Type hint for Tuple in _reorder_indexer

Author: nrebena

pandas/core/indexes/multi.py

@@ -3129,7 +3129,7 @@ def _reorder_indexer(
         indexer : a sorted Int64Index indexer of self ordered as seq
         """
         n = len(self)
-        keys = tuple()
+        keys = tuple()  # type: Tuple[np.ndarray, ...]
         # For each level of the sequence in seq, map the level codes with the
         # order they appears in a list-like sequence
         # This mapping is then use to reorder the indexer