class_docstr: Base class for all variational layers.
code: def prior(self):
      return self._prior
  
imports: import collections
  import tensorflow.compat.v2
  from tensorflow_probability.python import random
  from tensorflow_probability.python.distributions import distribution
  from tensorflow_probability.python.distributions import independent
  from tensorflow_probability.python.distributions import mvn_diag
  from tensorflow_probability.python.distributions import normal
  from tensorflow_probability.python.experimental.nn import layers
  from tensorflow_probability.python.internal import prefer_static
  from tensorflow_probability.python.util.seed_stream import SeedStream
label_desc: Use image node_id 4 for calling the VariationalLayer obj's underlying member method code with example usage: obj.prior() and returns: self