<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def filter_zone(self, data):
 """Check if a zone is private"""

        if self.private_zone is not None:
            if data['Config']['PrivateZone'] != self.str2bool(self.private_zone):
                return False

        if data['Name'] != '{0}.'.format(self.domain):
            return False

        return True