code: def test_himmelblau_v4(self):
      self._check_algorithm(
          func=_himmelblau,
          start_point=[3, -1],
          expected_argmin=[3.584428, -1.848126],
          gtol=1e-8,
      )
  
imports: import numpy
  import tensorflow.compat.v2
  import tf_quant_finance
  from tensorflow.python.framework import test_util
label_desc: Use image node_id 13 for calling the ConjugateGradientTest obj's underlying member method code with example usage: obj.test_himmelblau_v4() without return types