message: Minor tidy up of kwarg handling for map_structure.
diff: @@ -507,11 +507,9 @@ def map_structure(func, *structure, **kwargs):
  if not structure:
  raise ValueError("Must provide at least one structure")
  - check_types = True
  - expand_composites = False
  - if kwargs:
  - check_types = kwargs.pop("check_types", check_types)
  - expand_composites = kwargs.pop("expand_composites", expand_composites)
  + check_types = kwargs.pop("check_types", True)
  + expand_composites = kwargs.pop("expand_composites", False)
  +
  if kwargs:
  raise ValueError(
  "Only valid keyword arguments are `check_types` and "
  