code: def add_vnode(graph, num_vnode=1):
      """add_vnode"""
  
      num_nodes = graph.num_nodes + num_vnode
  
      src = np.tile(np.arange(num_nodes), [num_vnode, 1]).reshape(-1)
      dst = np.tile(
          np.arange(graph.num_nodes, num_nodes), [num_nodes, 1]
      ).T.reshape(-1)
      new_edges = np.stack([src, dst]).T
      edges = np.vstack((graph.edges, new_edges))
  
      g = pgl.graph.Graph(num_nodes=num_nodes, edges=edges)
  
      for k, v in graph._node_feat.items():
          new_feat = np.tile(v.mean(0), [num_vnode, 1])
          print(new_feat.shape)
          v = np.concatenate([v, new_feat])
          g._node_feat[k] = v
      return g
  
imports: import numpy
  import pgl
  import paddle.fluid
label_desc: Use image node_id 4 for calling a global function with example usage: add_vnode(graph, num_vnode) and returns: g