Set an expire flag on key ``name``. ``when`` can be represented
        as an integer representing unix time in milliseconds (unix time * 1000)
        or a Python datetime object.

def pexpireat(self, name, when):
        """
        Set an expire flag on key ``name``. ``when`` can be represented
        as an integer representing unix time in milliseconds (unix time * 1000)
        or a Python datetime object.
        """
        if isinstance(when, datetime.datetime):
            ms = int(when.microsecond / 1000)
            when = int(mod_time.mktime(when.timetuple())) * 1000 + ms
        return self.execute_command('PEXPIREAT', name, when)