class_docstr: Graph Dataloader
      
class_docstr_tok: ["Graph","Dataloader"]
docstr: __len__
docstr_tok: ["__len__"]
code: def __len__(self):
      """__len__"""
      return len(self.dataset)
  
file_path: PGL/legacy/examples/SAGPool/dataloader.py
imports: import numpy
  import collections
  import paddle
  import pgl
  from pgl.utils.logger import log
  from pgl.graph import Graph, MultiGraph
label_desc: Use image node_id 4 for calling the GraphDataloader obj's underlying member method code with example usage: obj.__len__() and returns: len