code: def testQuantileFiniteGradientAtDifficultPointsFloat64(self):
      self._baseQuantileFiniteGradientAtDifficultPoints(np.float64)
  
imports: import math
  import numpy
  from scipy import stats
  import tensorflow.compat.v1
  import tensorflow.compat.v2
  from tensorflow_probability.python.distributions import kullback_leibler
  from tensorflow_probability.python.distributions import normal
  from tensorflow_probability.python.internal import test_util
  from tensorflow_probability.python.math import gradient
label_desc: Use image node_id 20 for calling the NormalTest obj's underlying member method code with example usage: obj.testQuantileFiniteGradientAtDifficultPointsFloat64() without return types