<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _parse_ergodic_cutoff(self):
 """Get a numeric value from the ergodic_cutoff input, which can be 'on' or 'off'. """

        ec_is_str = isinstance(self.ergodic_cutoff, str)
        if ec_is_str and self.ergodic_cutoff.lower() == 'on':
            if self.sliding_window:
                return 1.0 / self.lag_time
            else:
                return 1.0
        elif ec_is_str and self.ergodic_cutoff.lower() == 'off':
            return 0.0
        else:
            return self.ergodic_cutoff