code: def test_bfloat16_to_float32(self, f):
      f32 = np.float32(f)
      bf16 = helper.float32_to_bfloat16(f32)
      assert isinstance(bf16, int)
      f32_1 = numpy_helper.bfloat16_to_float32(np.array([bf16]))[0]
      f32_2 = bfloat16_to_float32(bf16)
      if np.isnan(f32):
          assert np.isnan(f32_1)
          assert np.isnan(f32_2)
      else:
          self.assertEqual(f32, f32_1)
          self.assertEqual(f32, f32_2)
  
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 15 for calling the TestNumpyHelper obj's underlying member method code with example usage: obj.test_bfloat16_to_float32(f) without return types