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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def add_securitygroup_rule(self, group_id, remote_ip=None, remote_group=None, direction=None, ethertype=None, port_max=None, port_min=None, protocol=None):
 """Add a rule to a security group :param int group_id: The ID of the security group to add this rule to :param str remote_ip: The remote IP or CIDR to enforce the rule on :param int remote_group: The remote security group ID to enforce the rule on :param str direction: The direction to enforce (egress or ingress) :param str ethertype: The ethertype to enforce (IPv4 or IPv6) :param int port_max: The upper port bound to enforce (icmp code if the protocol is icmp) :param int port_min: The lower port bound to enforce (icmp type if the protocol is icmp) :param str protocol: The protocol to enforce (icmp, udp, tcp) """

        rule = {'direction': direction}
        if ethertype is not None:
            rule['ethertype'] = ethertype
        if port_max is not None:
            rule['portRangeMax'] = port_max
        if port_min is not None:
            rule['portRangeMin'] = port_min
        if protocol is not None:
            rule['protocol'] = protocol
        if remote_ip is not None:
            rule['remoteIp'] = remote_ip
        if remote_group is not None:
            rule['remoteGroupId'] = remote_group
        return self.add_securitygroup_rules(group_id, [rule])