def METHOD_NAME(self):
    self.fields = self.fields.lower().strip().split(",")
    self.policy = self.policy.lower().strip().split(",")
    if len(self.fields) != len(self.policy):
        raise ValueError("Length of parameters 'fields' (%d) and 'policy' (%d) is unequal."
                         "" % (len(self.fields), len(self.policy)))
    self.ip_networks = [ipaddress.ip_network(iprange) for iprange in NETWORKS]