Get a time string (24h format by default)
        :param pattern format
        :example '15:02:34'

def time(self, pattern='%H:%M:%S', end_datetime=None):
        """
        Get a time string (24h format by default)
        :param pattern format
        :example '15:02:34'
        """
        return self.date_time(
            end_datetime=end_datetime).time().strftime(pattern)