class_docstr: Sequential RNNLM.
  
  See also:
      https://github.com/pytorch/examples/blob/4581968193699de14b56527296262dd76ab43557/word_language_model/model.py
docstr: Initialize LM state filled with zero values.
code: def zero_state(self):
      """Initialize LM state filled with zero values."""
      if isinstance(self.rnn, torch.nn.LSTM):
          h = torch.zeros((self.nlayers, self.nhid), dtype=torch.float)
          c = torch.zeros((self.nlayers, self.nhid), dtype=torch.float)
          state = h, c
      else:
          state = torch.zeros(
              (self.nlayers, self.nhid), dtype=torch.float
          )
  
      return state
  
file_path: espnet/espnet2/lm/seq_rnn_lm.py
imports: from typing import Tuple, Union
  import torch
  import torch.nn
  from typeguard import check_argument_types
  from espnet2.lm.abs_model import AbsLM
label_desc: Use image node_id 2 for calling the SequentialRNNLM obj's underlying member method code with example usage: obj.zero_state() and returns: state