docstr: Gets called at the beginning of each epoch
docstr_tok: ["Gets","called","at","the","beginning","of","each","epoch"]
code: def on_stage_start(self, stage, epoch):
      """Gets called at the beginning of each epoch"""
  
      if stage != sb.Stage.TRAIN:
          self.cer_metric = self.hparams.cer_computer()
          self.wer_metric = self.hparams.error_rate_computer()
  
file_path: speechbrain/recipes/fluent-speech-commands/direct/train.py
imports: import sys
  import torch
  import speechbrain
  import logging
  from hyperpyyaml import load_hyperpyyaml
  from speechbrain.utils.distributed import run_on_main, if_main_process
label_desc: Use image node_id 3 for calling the SLU obj's underlying member method code with example usage: obj.on_stage_start(stage, epoch) without return types