docstr: Gets called when a stage (either training, validation, test) starts.
docstr_tok: ["Gets","called","when","a","stage","(","either","training",",","validation",",","test",")","starts","."]
code: def on_stage_start(self, stage, epoch):
      """Gets called when a stage (either training, validation, test) starts."""
      self.bleu_metric = self.hparams.bleu_computer()
  
      if stage != sb.Stage.TRAIN:
          self.acc_metric = self.hparams.acc_computer()
          self.bleu_metric = self.hparams.bleu_computer()
  
file_path: speechbrain/recipes/IWSLT22_lowresource/AST/transformer/train_with_samu_mbart.py
imports: import sys
  import torch
  import logging
  import speechbrain
  from speechbrain.utils.distributed import run_on_main
  from hyperpyyaml import load_hyperpyyaml
  from sacremoses import MosesDetokenizer
  from torch.nn.parallel import DistributedDataParallel
label_desc: Use image node_id 5 for calling the ST obj's underlying member method code with example usage: obj.on_stage_start(stage, epoch) without return types