code: def _get_input_names(onnx_model):
      return {i.name for i in onnx_model.graph.input}
  
imports: import glob
  import os
  import unittest
  import chainer
  import numpy
  import onnx
  import pytest
  from onnx_chainer.testing.get_test_data_set import gen_test_data_set
label_desc: Use image node_id 4 for calling a global function with example usage: _get_input_names(onnx_model) and returns: unknown