class_docstr: WordTensorGenerator generates string tf.Tensor with string
  length similar to a word.
code: def generate(self):
      # Use Poisson distribution to sample the length of byte strings.
      # The avg_length equals to the lambda in Poisson distribution.
      shape = self.spec.shape.as_list()
      lengths = np.random.poisson(self._avg_length, size=shape)
  
      to_string = lambda length: np.random.bytes(length)
      vfunc = np.vectorize(to_string)
      values = vfunc(lengths)
  
      return tf.convert_to_tensor(
          values, dtype=tf.string, name=self.spec.name
      )
  
imports: import hashlib
  import numpy
  import tensorflow
  from tests.test_atds_avro.utils.generator.generator_base import Generator
  from tests.test_atds_avro.utils.hash_util import int_to_bytes
label_desc: Use image node_id 2 for calling the WordTensorGenerator obj's underlying member method code with example usage: obj.generate() and returns: tf