copy = key_placeholder;
            node_map[n] = copy;
          } else {
            // Copy the node.
            NodeDef copy_def = n->def();
            // Change c).
            copy_def.clear_device();
            copy = (*host_graph)->AddNode(copy_def, &s);
            if (!s.ok()) {
              return;
            }
            node_map[n] = copy;
          }