Reset the loaded state of the configuration to what it was at import.

    Note that this does *not* reset values set by commandline flags or loaded
    from --config-file (in fact, any values loaded from --config-file that have
    been overridden are reset to their value from --config-file).

def reset(self):
    """Reset the loaded state of the configuration to what it was at import.

    Note that this does *not* reset values set by commandline flags or loaded
    from --config-file (in fact, any values loaded from --config-file that have
    been overridden are reset to their value from --config-file).
    """
    # Populate loaded_values with values from --config-file, if it was given.
    self._loaded_values = {}
    if self._flags.config_file is not None:
      self.load_from_file(self._flags.config_file, _allow_undeclared=True)