docstr: Given the network predictions and targets computed the CE loss.
code: def compute_objectives(self, predictions, batch, stage):
      "Given the network predictions and targets computed the CE loss."
      predictions, lens = predictions
      spkid, spkid_lens = batch.spk_id_encoded
      loss = self.hparams.compute_cost(predictions, spkid, lens)
  
      if stage != sb.Stage.TRAIN:
          self.error_metrics.append(batch.id, predictions, spkid, lens)
  
      return loss
  
file_path: speechbrain/tests/integration/speaker_id/example_xvector_experiment.py
imports: import pathlib
  import speechbrain
  from hyperpyyaml import load_hyperpyyaml
label_desc: Use image node_id 2 for calling the XvectorBrain obj's underlying member method code with example usage: obj.compute_objectives(predictions, batch, stage) and returns: loss