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.
      
code: def dump(self, path):
      if self._is_tensor:
          edge_index = self.numpy(inplace=False)
          edge_index.dump(path)
      else:
          if not os.path.exists(path):
              os.makedirs(path)
          np.save(os.path.join(path, "degree.npy"), self._degree)
          np.save(os.path.join(path, "sorted_v.npy"), self._sorted_v)
          np.save(os.path.join(path, "sorted_u.npy"), self._sorted_u)
          np.save(
              os.path.join(path, "sorted_eid.npy"), self._sorted_eid
          )
          np.save(os.path.join(path, "indptr.npy"), self._indptr)
  
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 11 for calling the EdgeIndex obj's underlying member method code with example usage: obj.dump(path) without return types