class_docstr: Decoder module of Spectrogram prediction network.
  
  This is a module of decoder of Spectrogram prediction network in Tacotron2,
  which described in `Natural TTS
  Synthesis by Conditioning WaveNet on Mel Spectrogram Predictions`_.
  The decoder generates the sequence of
  features from the sequence of the hidden states.
  
  .. _`Natural TTS Synthesis by Conditioning WaveNet on Mel Spectrogram Predictions`:
     https://arxiv.org/abs/1712.05884
code: def _zero_state(self, hs):
      init_hs = hs.new_zeros(hs.size(0), self.lstm[0].hidden_size)
      return init_hs
  
imports: import torch
  import torch.nn.functional
  from espnet.nets.pytorch_backend.rnn.attentions import AttForwardTA
label_desc: Use image node_id 2 for calling the Decoder obj's underlying member method code with example usage: obj._zero_state(hs) and returns: init_hs