def add_all(self, items):
check_not_none(items, "<STR_LIT>")<EOL>data_items = []<EOL>for item in items:<EOL><INDENT>check_not_none(item, "<STR_LIT>")<EOL>data_items.append(self._to_data(item))<EOL><DEDENT>return self._encode_invoke(set_add_all_codec, value_list=data_items)<EOL>
Adds the elements in the specified collection if they're not exist in this set.

:param items: (Collection), collection which includes the items to be added.
:return: (bool), ``true`` if this set is changed after call, ``false`` otherwise.