code: def take_step(self, state, max_actions=None, allowed_actions=None):
      indexed_next_states = defaultdict(list)
      if not allowed_actions:
          allowed_actions = [None] * len(state.batch_indices)
      for (
          batch_index,
          action_history,
          score,
          start_value,
          actions,
      ) in izip(
          state.batch_indices,
          state.action_history,
          state.score,
          state.start_values,
          allowed_actions,
      ):
          prev_action = (
              action_history[-1] if action_history else start_value
          )
          for action in self._valid_actions:
              next_item = int(prev_action + action)
              if actions and next_item not in actions:
                  continue
              new_history = action_history + [next_item]
              # For every action taken, we reduce the score by 1.
              new_score = score - 1
              if self._include_value_in_score:
                  new_score += 0.01 * next_item
              new_state = SimpleDecoderState(
                  [batch_index], [new_history], [new_score]
              )
              indexed_next_states[batch_index].append(new_state)
      next_states = []
      for batch_next_states in list(indexed_next_states.values()):
          sorted_next_states = [
              (-state.score[0].data[0], state)
              for state in batch_next_states
          ]
          sorted_next_states.sort(key=lambda x: x[0])
          if max_actions is not None:
              sorted_next_states = sorted_next_states[:max_actions]
          next_states.extend(state[1] for state in sorted_next_states)
      return next_states
  
file_path: magnitude/pymagnitude/third_party/allennlp/tests/nn/decoding/simple_transition_system.py
imports: from __future__ import absolute_import
  from collections import defaultdict
  import torch
  from allennlp.nn.decoding import DecoderState, DecoderStep
label_desc: Use image node_id 2 for calling the SimpleDecoderStep obj's underlying member method code with example usage: obj.take_step(state, max_actions, allowed_actions) and returns: next_states