code: def _all_names_in_net(net):
      if net is None:
          return set()
  
      names = set()
      names.update(net.external_input)
      names.update(net.external_output)
      for op in net.op:
          names.update(op.input)
          names.update(op.output)
      return names
  
imports: import collections
  import itertools
  import logging
  import re
  from caffe2.python import core
  from onnx import checker, helper, numpy_helper, mapping, GraphProto, NodeProto, TensorProto, OperatorSetIdProto
  from onnx.helper import make_tensor_value_info, make_model
  import numpy
  from caffe2.python.onnx.helper import c2_native_run_net
  import caffe2.python._import_c_extension
label_desc: Use image node_id 6 for calling the Caffe2Frontend obj's underlying member method code with example usage: obj._all_names_in_net(net) and returns: names, set