docstr: Adds a training step prefix to every key in the provided statistics
  dictionary
  
  Arguments
  ---------
  stats: dict
      a statistics dictionary
  
  Returns
  ---------
  stats: dict
      a prefixed statistics dictionary
docstr_tok: ["Adds","a","training","step","prefix","to","every","key","in","the","provided","statistics","dictionary","Arguments","--","--","--","--","-","stats",":","dict","a","statistics","dictionary","Returns","--","--","--","--","-","stats",":","dict","a","prefixed","statistics","dictionary"]
code: def _add_stats_prefix(self, stats):
      """
      Adds a training step prefix to every key in the provided statistics
      dictionary
  
      Arguments
      ---------
      stats: dict
          a statistics dictionary
  
      Returns
      ---------
      stats: dict
          a prefixed statistics dictionary
      """
      prefix = self.train_step["name"]
      return {
          stage: {
              f"{prefix}_{key}": value
              for key, value in stage_stats.items()
          }
          for stage, stage_stats in stats.items()
      }
  
imports: from speechbrain.dataio.dataset import FilteredSortedDynamicItemDataset, DynamicItemDataset
  from speechbrain.dataio.sampler import BalancingDataSampler
  from speechbrain.utils.data_utils import undo_padding
  import datasets
  import logging
  import os
  import random
  import speechbrain
  import sys
  from enum import Enum
  from collections import namedtuple
  from hyperpyyaml import load_hyperpyyaml
  from functools import partial
  from speechbrain.utils.distributed import run_on_main
  from speechbrain.utils.pretrained import save_for_pretrained
  from speechbrain.lobes.models.g2p.dataio import enable_eos_bos, grapheme_pipeline, phoneme_pipeline, tokenizer_encode_pipeline, add_bos_eos, get_sequence_key, phonemes_to_label
  from speechbrain.dataio.wer import print_alignments
  from speechbrain.wordemb.util import expand_to_chars
  from io import StringIO
  from speechbrain.utils import hpopt
  import numpy
label_desc: Use image node_id 19 for calling the G2PBrain obj's underlying member method code with example usage: obj._add_stats_prefix(stats) and returns: unknown