code: def gen_extra_context(self, *args):
      super().gen_extra_context()
      self.all_context[
          "predicted_length"
      ] = self.all_target_length_preds
      self.all_context["target_length"] = self.all_target_lens
      self.all_context["topk_tree_predictions"] = self.all_preds
  
imports: from collections import defaultdict
  from typing import Dict, List
  import numpy
  from pytext.common.constants import Stage
  from pytext.data.tensorizers import Tensorizer
  from pytext.metric_reporters.channel import ConsoleChannel
  from pytext.metric_reporters.compositional_metric_reporter import CompositionalMetricReporter
  from pytext.metric_reporters.seq2seq_compositional import CompositionalSeq2SeqFileChannel, Seq2SeqCompositionalMetricReporter
  from pytext.metrics.intent_slot_metrics import FramePredictionPair
  from pytext.metrics.mask_metrics import compute_masked_metrics, compute_nas_masked_metrics
  from .compositional_utils import extract_beam_subtrees, filter_invalid_beams
label_desc: Use image node_id 12 for calling the MaskedSeq2SeqCompositionalMetricReporter obj's underlying member method code with example usage: obj.gen_extra_context() without return types