code: def test_float8_e4m3fn_inf(self):
      x = np.float32(np.inf)
      to = helper.float32_to_float8e4m3(x)
      back = numpy_helper.float8e4m3_to_float32(to)
      self.assertEqual(back, 448)
  
      x = np.float32(np.inf)
      to = helper.float32_to_float8e4m3(x, saturate=False)
      back = numpy_helper.float8e4m3_to_float32(to)
      self.assertTrue(np.isnan(back))
  
      x = np.float32(-np.inf)
      to = helper.float32_to_float8e4m3(x)
      self.assertEqual(to & 0x80, 0x80)
      back = numpy_helper.float8e4m3_to_float32(to)
      self.assertEqual(back, -448)
  
      x = np.float32(-np.inf)
      to = helper.float32_to_float8e4m3(x, saturate=False)
      self.assertEqual(to & 0x80, 0x80)
      back = numpy_helper.float8e4m3_to_float32(to)
      self.assertTrue(np.isnan(back))
  
imports: import unittest
  from typing import Any
  import numpy
  import parameterized
  import onnx
  from onnx import helper, numpy_helper
label_desc: Use image node_id 19 for calling the TestNumpyHelper obj's underlying member method code with example usage: obj.test_float8_e4m3fn_inf() without return types