class_docstr: Indexing edges for fast graph queries
  Sorted edges and represent edges in compressed style like csc_matrix or csr_matrix.
  
      Args:
          u: A list of node id to be compressed.
          v: A list of node id that are connected with u.
          num_nodes: The exactive number of nodes.
      
docstr: Return whether the graph is paddle.Tensor or numpy.
          
docstr_tok: ["Return","whether","the","graph","is","paddle.Tensor","or","numpy","."]
code: def is_tensor(self):
      """Return whether the graph is paddle.Tensor or numpy."""
      return self._is_tensor
  
imports: import os
  import json
  import copy
  import numpy
  import paddle
  from paddle.framework import core
  from pgl.utils import op
  import pgl.graph_kernel
  from pgl.utils.helper import check_is_tensor, to_paddle_tensor
label_desc: Use image node_id 8 for calling the EdgeIndex obj's underlying member method code with example usage: obj.is_tensor() and returns: self