code: def get_firewall_rule(self, server_uuid, firewall_rule_position, server_instance=None):
          
          url = '/server/{0}/firewall_rule/{1}'.format(server_uuid, firewall_rule_position)
          res = self.get_request(url)
          return FirewallRule(**res['firewall_rule'])
docs: Return a FirewallRule object based on server uuid and rule position.