code: def get_fw(self, fw_id):
          
          fw = None
          try:
              fw = self.neutronclient.show_firewall(fw_id)
          except Exception as exc:
              LOG.error("Failed to get firewall list for id %(id)s, "
                        "Exc %(exc)s", {'id': fw_id, 'exc': str(exc)})
          return fw
docs: Return the Firewall given its ID.