firewallrule.go
func (c *Client) GetFirewallRule(dcID string, serverID string, nicID string, fwID string) (*FirewallRule, error) {
	url := fwrulePath(dcID, serverID, nicID, fwID) + `?depth=` + c.client.depth + `&pretty=` + strconv.FormatBool(c.client.pretty)
	ret := &FirewallRule{}
	err := c.client.Get(url, ret, http.StatusOK)
	return ret, err
}
func (c *Client) GetFirewallRule(dcID string, serverID string, nicID string, fwID string) (*FirewallRule, error) {
	url := fwrulePath(dcID, serverID, nicID, fwID) + `?depth=` + c.client.depth + `&pretty=` + strconv.FormatBool(c.client.pretty)
	ret := &FirewallRule{}
	err := c.client.Get(url, ret, http.StatusOK)
	return ret, err
}
//GetFirewallRule gets a firewall rule