<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def strip_datetime(value):
 """ Converts value to datetime if string or int. """

        if isinstance(value, basestring):
            try:
                return parse_datetime(value)
            except ValueError:
                return
        elif isinstance(value, integer_types):
            try:
                return datetime.datetime.utcfromtimestamp(value / 1e3)
            except (ValueError, OverflowError, OSError):
                return