docs: def validate_is_document_type(option, value):
      """Validate the type of method arguments that expect a MongoDB document."""
      if not isinstance(value, (collections.MutableMapping, RawBSONDocument)):
          raise TypeError("%s must be an instance of dict, bson.son.SON, "
                          "bson.raw_bson.RawBSONDocument, or "
                          "a type that inherits from "
                          "collections.MutableMapping" % (option,))