def METHOD_NAME(self):
    """Record the results of a stopwatch. For perf testing.
    This keyword uses Set Test Elapsed Time internally and therefore
    outputs in all of the ways described there.
    Example:
    | Start Performance Timer
    | Do Something
    | Stop Performance Timer
    """
    start_time = self.builtin.get_variable_value("${__start_time}")
    if start_time:
        seconds = (datetime.now() - start_time).seconds
        assert seconds is not None
        self.set_test_elapsed_time(seconds)
    else:
        raise Exception(
            "Elapsed time clock was not started. "
            "Use the Start Elapsed Time keyword to do so."
        )