class_docstr: Tests a single step of beam search
    
code: def setUp(self):
      super(TestBeamStep, self).setUp()
      self.state_size = 10
      config = beam_search.BeamSearchConfig(
          beam_width=3,
          vocab_size=5,
          eos_token=0,
          length_penalty_weight=0.6,
          choose_successors_fn=beam_search.choose_top_k,
      )
      self.config = config
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from __future__ import unicode_literals
  import tensorflow
  import numpy
  from seq2seq.inference import beam_search
label_desc: Use image node_id 1 for calling the TestBeamStep obj's underlying member method code with example usage: obj.setUp() without return types