code: def setUp(self):
      super(PoissonTest, self).setUp()
      self.dtype = np.float32
      self.model = family.Poisson()
      self.expected = family.CustomExponentialFamily(
          lambda mean: poisson.Poisson(rate=mean), tf.math.exp
      )
  
imports: import numpy
  import tensorflow.compat.v2
  from tensorflow_probability.python.distributions import bernoulli
  from tensorflow_probability.python.distributions import binomial
  from tensorflow_probability.python.distributions import gamma
  from tensorflow_probability.python.distributions import lognormal
  from tensorflow_probability.python.distributions import negative_binomial
  from tensorflow_probability.python.distributions import normal
  from tensorflow_probability.python.distributions import poisson
  from tensorflow_probability.python.glm import family
  from tensorflow_probability.python.internal import test_util
label_desc: Use image node_id 1 for calling the PoissonTest obj's underlying member method code with example usage: obj.setUp() without return types