docstr: Number of hypotheses in the list.
code: def hypo_len(self, hypo_idx: int):
      """
      Number of hypotheses in the list.
      """
      return self._beam_hyps_count[hypo_idx]
  
imports: import copy
  import itertools
  from typing import List, Optional, Tuple
  import torch
  import torch.nn.functional
  from transformers import BartConfig
  from transformers.generation import GenerationMixin
label_desc: Use image node_id 4 for calling the BeamSearchScorerTS obj's underlying member method code with example usage: obj.hypo_len(hypo_idx) and returns: self