<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def lock_up_period(self, lock_up_period):
 """ This lockup period is in months. This might change to a relative delta."""

        try:
            if isinstance(lock_up_period, (str, int)):
                self._lock_up_period = int(lock_up_period)
        except Exception:
            raise ValueError('invalid input of lock up period %s, cannot be converted to an int' %
                             lock_up_period)