code: def add_interval_stat(rl_tuner, action, stat_dict, key=None):
      """Computes the melodic interval just played and adds it to a stat dict.
  
      Args:
        rl_tuner: An RLTuner object.
        action: One-hot encoding of the chosen action.
        stat_dict: A dictionary containing fields for statistics about
          compositions.
        key: The numeric values of notes belonging to this key. Defaults to
          C-major if not provided.
      Returns:
        A dictionary of composition statistics with fields updated to include new
        intervals.
      """
      interval, _, _ = rl_tuner.detect_sequential_interval(action, key)
  
      if interval == 0:
          return stat_dict
  
      if interval == rl_tuner_ops.REST_INTERVAL:
          stat_dict["num_rest_intervals"] += 1
      elif interval == rl_tuner_ops.REST_INTERVAL_AFTER_THIRD_OR_FIFTH:
          stat_dict["num_special_rest_intervals"] += 1
      elif interval > rl_tuner_ops.OCTAVE:
          stat_dict["num_octave_jumps"] += 1
      elif interval == (
          rl_tuner_ops.IN_KEY_FIFTH
          or interval == rl_tuner_ops.IN_KEY_THIRD
      ):
          stat_dict["num_in_key_preferred_intervals"] += 1
      elif interval == rl_tuner_ops.FIFTH:
          stat_dict["num_fifths"] += 1
      elif interval == rl_tuner_ops.THIRD:
          stat_dict["num_thirds"] += 1
      elif interval == rl_tuner_ops.SIXTH:
          stat_dict["num_sixths"] += 1
      elif interval == rl_tuner_ops.SECOND:
          stat_dict["num_seconds"] += 1
      elif interval == rl_tuner_ops.FOURTH:
          stat_dict["num_fourths"] += 1
      elif interval == rl_tuner_ops.SEVENTH:
          stat_dict["num_sevenths"] += 1
  
      return stat_dict
  
file_path: magenta/magenta/models/rl_tuner/rl_tuner_eval_metrics.py
imports: from magenta.models.rl_tuner import rl_tuner_ops
  import numpy
  import tensorflow.compat.v1
label_desc: Use image node_id 5 for calling a global function with example usage: add_interval_stat(rl_tuner, action, stat_dict, key) and returns: stat_dict, stat_dict