<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def update_parser(self, parser):
 """Update config dictionary with declared arguments in an argparse.parser New variables will be created, and existing ones overridden. Args: parser (argparse.ArgumentParser):
 parser to read variables from """


        self._parser = parser
        ini_str = argparse_to_ini(parser)
        configp = configparser.ConfigParser(allow_no_value=True)
        configp.read_dict(self._config)
        configp.read_string(ini_str)
        self._config.update(
            {s: dict(configp.items(s))
             for s in configp.sections()}
        )