docstr: build graph for pytorch
code: def build(self, shape):
      """
      build graph for pytorch
      """
      import re
  
      # construct graph
      dummy_input = torch.autograd.Variable(
          torch.randn(shape), requires_grad=False
      )
  
      graph, nodes = self.extractgraph(dummy_input)
  
      # build each layer
      for node in nodes:
          node_id = PytorchGraph.get_node_id(node)
          node_name = self.rename_nodes(node, node_id)
          output_str = node.__str__().split("=")[0]
          output_shape_str = re.findall(r"[^()!]+", output_str)
          if len(output_shape_str) > 1:
              output_shape = [
                  int(x.replace("!", ""))
                  for x in output_shape_str[1].split(",")
              ]
          else:
              output_shape = None
          self.shape_dict[node_name] = output_shape
          self.layer_map[node_name] = self.CreateGraphNode(node)
          self.layer_name_map[node_name] = node_name
          # make connection
          self.node_connection(graph, node, node_name)
  
      super(PytorchGraph, self).build()
  
imports: from mmdnn.conversion.common.DataStructure.graph import GraphNode, Graph
  import torch
  import torch.autograd
  import torch.serialization
  import contextlib
  from torch.jit import _unique_state_dict
label_desc: Use image node_id 3 for calling the PytorchGraph obj's underlying member method code with example usage: obj.build(shape) without return types