@classmethod<EOL><INDENT>def load_index(cls, index_name):<DEDENT>
cls._load_from_file()<EOL>if index_name not in cls._mock_elastic:<EOL><INDENT>cls._mock_elastic[index_name] = {}<EOL>cls._write_to_file()<EOL><DEDENT>return cls._mock_elastic[index_name]<EOL>
load the index, if necessary from the backed file