code: def add_interface_router(self, router, subnet):
          '''
          Adds an internal network interface to the specified router
          '''
          router_id = self._find_router_id(router)
          subnet_id = self._find_subnet_id(subnet)
          return self.network_conn.add_interface_router(
              router=router_id, body={'subnet_id': subnet_id}f add_interface_router(self, router, subnet):
          '''
          Adds an internal network interface to the specified router
          '''
          router_id = self._find_router_id(router)
          subnet_id = self._find_subnet_id(subnet)
          return self.network_conn.add_interface_router(
              router=router_id, body={'subnet_id': subnet_id})
docs: Adds an internal network interface to the specified router