def MergeMessage(<EOL>self, source, destination,<EOL>replace_message_field=False, replace_repeated_field=False):
tree = _FieldMaskTree(self)<EOL>tree.MergeMessage(<EOL>source, destination, replace_message_field, replace_repeated_field)<EOL>
Merges fields specified in FieldMask from source to destination.

        Args:
          source: Source message.
          destination: The destination message to be merged into.
          replace_message_field: Replace message field if True. Merge message
              field if False.
          replace_repeated_field: Replace repeated field if True. Append
              elements of repeated field if False.