class_docstr: Base class shared by Tacotron and Tacotron2
docstr: Run backwards decoder
docstr_tok: ["Run","backwards","decoder"]
code: def _backward_pass(self, mel_specs, encoder_outputs, mask):
      """Run backwards decoder"""
      decoder_outputs_b, alignments_b, _ = self.decoder_backward(
          encoder_outputs, torch.flip(mel_specs, dims=(1,)), mask
      )
      decoder_outputs_b = decoder_outputs_b.transpose(1, 2).contiguous()
      return decoder_outputs_b, alignments_b
  
imports: import copy
  from abc import abstractmethod
  from typing import Dict, Tuple
  import torch
  from coqpit import Coqpit
  from torch import nn
  from TTS.tts.layers.losses import TacotronLoss
  from TTS.tts.models.base_tts import BaseTTS
  from TTS.tts.utils.helpers import sequence_mask
  from TTS.tts.utils.speakers import SpeakerManager
  from TTS.tts.utils.synthesis import synthesis
  from TTS.tts.utils.text.tokenizer import TTSTokenizer
  from TTS.tts.utils.visual import plot_alignment, plot_spectrogram
  from TTS.utils.generic_utils import format_aux_input
  from TTS.utils.io import load_fsspec
  from TTS.utils.training import gradual_training_scheduler
label_desc: Use image node_id 13 for calling the BaseTacotron obj's underlying member method code with example usage: obj._backward_pass(mel_specs, encoder_outputs, mask) and returns: decoder_outputs_b,  alignments_b