code: import torch
  from torch import nn
  from torch.nn.functional import fold, unfold
  
  from . import norms, activations
  from .norms import GlobLN, CumLN
  from ..utils import has_arg
  
  
  class SingleRNN(nn.Module):
      """ Module for a RNN block.
  
      Inspired from https://github.com/yluo42/TAC/blob/master/utility/models.py
      Licensed under CC BY-NC-SA 3.0 US.
  
      Args:
          rnn_type (str): Select from ``'RNN'``, ``'LSTM'``, ``'GRU'``. Can
              also be passed in lowercase letters.
          input_size (int): Dimension of the input feature. The input should have
              shape [batch, seq_len, input_size].
          hidden_size (int): Dimension of the hidden state.
          n_layers (int, optional): Number of layers used in RNN. Default is 1.
          dropout (float, optional): Dropout ratio. Default is 0.
          bidirectional (bool, optional): Whether the RNN layers are
              bidirectional. Default is ``False``.
      """
  
      def __init__(
          self, rnn_type, input_size, hidden_size, n_layers=1, dropout=0, bidirectional=False
      ):
          super(SingleRNN, self).__init__()
          assert rnn_type.upper() in ["RNN", "LSTM", "GRU"]
          rnn_type = rnn_type.upper()
          self.rnn_type = rnn_type
          self.input_size = input_size
          self.hidden_size = hidden_size
          self.rnn = getattr(nn, rnn_type)(
              input_size,
              hidden_size,
              num_layers=n_layers,
              dropout=dropout,
              batch_first=True,
              bidirectional=bool(bidirectional),
          )
  
      def forward(self, inp):
          """ Input shape [batch, seq, feats] """
          self.rnn.flatten_parameters()  # Enables faster multi-GPU training.
          output = inp
          rnn_output, _ = self.rnn(output)
          return rnn_output
  
  
  class StackedResidualRNN(nn.Module):
      """ Stacked RNN with builtin residual connection.
      Only supports forward RNNs.
      See StackedResidualBiRNN for bidirectional ones.
  
      Args:
          rnn_type (str): Select from ``'RNN'``, ``'LSTM'``, ``'GRU'``. Can
              also be passed in lowercase letters.
          n_units (int): Number of units in recurrent layers. This will also be
              the expected input size.
          n_layers (int): Number of recurrent layers.
          dropout (float): Dropout value, between 0. and 1. (Default: 0.)
          bidirectional (bool): If True, use bidirectional RNN, else
              unidirectional. (Default: False)
      """
  
      def __init__(self, rnn_type, n_units, n_layers=4, dropout=0.0, bidirectional=False):
          super(StackedResidualRNN, self).__init__()
          self.rnn_type = rnn_type
          self.n_units = n_units
          self.n_layers = n_layers
          self.dropout = dropout
          assert bidirectional is False, "Bidirectional not supported yet"
          self.bidirectional = bidirectional
  
          self.layers = nn.ModuleList()
          for _ in range(n_layers):
              self.layers.append(
                  SingleRNN(
                      rnn_type, input_size=n_units, hidden_size=n_units, bidirectional=bidirectional
                  )
              )
          self.dropout_layer = nn.Dropout(self.dropout)
  
      def forward(self, x):
          """ Builtin residual connections + dropout applied before residual.
              Input shape : [batch, time_axis, feat_axis]
          """
          for rnn in self.layers:
              rnn_out = rnn(x)
              dropped_out = self.dropout_layer(rnn_out)
              x = x + dropped_out
          return x
  
  
  class StackedResidualBiRNN(nn.Module):
      """ Stacked Bidirectional RNN with builtin residual connection.
      Residual connections are applied on both RNN directions.
      Only supports bidiriectional RNNs.
      See StackedResidualRNN for unidirectional ones.
  
      Args:
          rnn_type (str): Select from ``'RNN'``, ``'LSTM'``, ``'GRU'``. Can
              also be passed in lowercase letters.
          n_units (int): Number of units in recurrent layers. This will also be
              the expected input size.
          n_layers (int): Number of recurrent layers.
          dropout (float): Dropout value, between 0. and 1. (Default: 0.)
          bidirectional (bool): If True, use bidirectional RNN, else
              unidirectional. (Default: False)
      """
  
      def __init__(self, rnn_type, n_units, n_layers=4, dropout=0.0, bidirectional=True):
          super().__init__()
          self.rnn_type = rnn_type
          self.n_units = n_units
          self.n_layers = n_layers
          self.dropout = dropout
          assert bidirectional is True, "Only bidirectional not supported yet"
          self.bidirectional = bidirectional
  
          # The first layer has as many units as input size
          self.first_layer = SingleRNN(
              rnn_type, input_size=n_units, hidden_size=n_units, bidirectional=bidirectional
          )
          # As the first layer outputs 2*n_units, the following layers need
          # 2*n_units as input size
          self.layers = nn.ModuleList()
          for i in range(n_layers - 1):
              input_size = 2 * n_units
              self.layers.append(
                  SingleRNN(
                      rnn_type,
                      input_size=input_size,
                      hidden_size=n_units,
                      bidirectional=bidirectional,
                  )
              )
          self.dropout_layer = nn.Dropout(self.dropout)
  
      def forward(self, x):
          """ Builtin residual connections + dropout applied before residual.
              Input shape : [batch, time_axis, feat_axis]
          """
          # First layer
          rnn_out = self.first_layer(x)
          dropped_out = self.dropout_layer(rnn_out)
          x = torch.cat([x, x], dim=-1) + dropped_out
          # Rest of the layers
          for rnn in self.layers:
              rnn_out = rnn(x)
              dropped_out = self.dropout_layer(rnn_out)
              x = x + dropped_out
          return x
  
  
  class DPRNNBlock(nn.Module):
      """ Dual-Path RNN Block as proposed in [1].
  
      Args:
          in_chan (int): Number of input channels.
          hid_size (int): Number of hidden neurons in the RNNs.
          norm_type (str, optional): Type of normalization to use. To choose from
              - ``'gLN'``: global Layernorm
              - ``'cLN'``: channelwise Layernorm
          bidirectional (bool, optional): True for bidirectional Inter-Chunk RNN.
          rnn_type (str, optional): Type of RNN used. Choose from ``'RNN'``,
              ``'LSTM'`` and ``'GRU'``.
          num_layers (int, optional): Number of layers used in each RNN.
          dropout (float, optional): Dropout ratio. Must be in [0, 1].
  
      References:
          [1] "Dual-path RNN: efficient long sequence modeling for
          time-domain single-channel speech separation", Yi Luo, Zhuo Chen
          and Takuya Yoshioka. https://arxiv.org/abs/1910.06379
      """
  
      def __init__(
          self,
          in_chan,
          hid_size,
          norm_type="gLN",
          bidirectional=True,
          rnn_type="LSTM",
          num_layers=1,
          dropout=0,
      ):
          super(DPRNNBlock, self).__init__()
          # IntraRNN and linear projection layer (always bi-directional)
          self.intra_RNN = SingleRNN(
              rnn_type, in_chan, hid_size, num_layers, dropout=dropout, bidirectional=True
          )
          self.intra_linear = nn.Linear(hid_size * 2, in_chan)
          self.intra_norm = norms.get(norm_type)(in_chan)
          # InterRNN block and linear projection layer (uni or bi-directional)
          self.inter_RNN = SingleRNN(
              rnn_type, in_chan, hid_size, num_layers, dropout=dropout, bidirectional=bidirectional
          )
          num_direction = int(bidirectional) + 1
          self.inter_linear = nn.Linear(hid_size * num_direction, in_chan)
          self.inter_norm = norms.get(norm_type)(in_chan)
  
      def forward(self, x):
          """ Input shape : [batch, feats, chunk_size, num_chunks] """
          B, N, K, L = x.size()
          output = x  # for skip connection
          # Intra-chunk processing
          x = x.transpose(1, -1).reshape(B * L, K, N)
          x = self.intra_RNN(x)
          x = self.intra_linear(x)
          x = x.reshape(B, L, K, N).transpose(1, -1)
          x = self.intra_norm(x)
          output = output + x
          # Inter-chunk processing
          x = output.transpose(1, 2).transpose(2, -1).reshape(B * K, L, N)
          x = self.inter_RNN(x)
          x = self.inter_linear(x)
          x = x.reshape(B, K, L, N).transpose(1, -1).transpose(2, -1)
          x = self.inter_norm(x)
          return output + x
  
  
  class DPRNN(nn.Module):
      """ Dual-path RNN Network for Single-Channel Source Separation
          introduced in [1].
  
      Args:
          in_chan (int): Number of input filters.
          n_src (int): Number of masks to estimate.
          out_chan  (int or None): Number of bins in the estimated masks.
              Defaults to `in_chan`.
          bn_chan (int): Number of channels after the bottleneck.
              Defaults to 128.
          hid_size (int): Number of neurons in the RNNs cell state.
              Defaults to 128.
          chunk_size (int): window size of overlap and add processing.
              Defaults to 100.
          hop_size (int or None): hop size (stride) of overlap and add processing.
              Default to `chunk_size // 2` (50% overlap).
          n_repeats (int): Number of repeats. Defaults to 6.
          norm_type (str, optional): Type of normalization to use. To choose from
  
              - ``'gLN'``: global Layernorm
              - ``'cLN'``: channelwise Layernorm
          mask_act (str, optional): Which non-linear function to generate mask.
          bidirectional (bool, optional): True for bidirectional Inter-Chunk RNN
              (Intra-Chunk is always bidirectional).
          rnn_type (str, optional): Type of RNN used. Choose between ``'RNN'``,
              ``'LSTM'`` and ``'GRU'``.
          num_layers (int, optional): Number of layers in each RNN.
          dropout (float, optional): Dropout ratio, must be in [0,1].
  
      References:
          [1] "Dual-path RNN: efficient long sequence modeling for
              time-domain single-channel speech separation", Yi Luo, Zhuo Chen
              and Takuya Yoshioka. https://arxiv.org/abs/1910.06379
      """
  
      def __init__(
          self,
          in_chan,
          n_src,
          out_chan=None,
          bn_chan=128,
          hid_size=128,
          chunk_size=100,
          hop_size=None,
          n_repeats=6,
          norm_type="gLN",
          mask_act="relu",
          bidirectional=True,
          rnn_type="LSTM",
          num_layers=1,
          dropout=0,
      ):
          super(DPRNN, self).__init__()
          self.in_chan = in_chan
          out_chan = out_chan if out_chan is not None else in_chan
          self.out_chan = out_chan
          self.bn_chan = bn_chan
          self.hid_size = hid_size
          self.chunk_size = chunk_size
          hop_size = hop_size if hop_size is not None else chunk_size // 2
          self.hop_size = hop_size
          self.n_repeats = n_repeats
          self.n_src = n_src
          self.norm_type = norm_type
          self.mask_act = mask_act
          self.bidirectional = bidirectional
          self.rnn_type = rnn_type
          self.num_layers = num_layers
          self.dropout = dropout
  
          layer_norm = norms.get(norm_type)(in_chan)
          bottleneck_conv = nn.Conv1d(in_chan, bn_chan, 1)
          self.bottleneck = nn.Sequential(layer_norm, bottleneck_conv)
  
          # Succession of DPRNNBlocks.
          net = []
          for x in range(self.n_repeats):
              net += [
                  DPRNNBlock(
                      bn_chan,
                      hid_size,
                      norm_type=norm_type,
                      bidirectional=bidirectional,
                      rnn_type=rnn_type,
                      num_layers=num_layers,
                      dropout=dropout,
                  )
              ]
          self.net = nn.Sequential(*net)
          # Masking in 3D space
          net_out_conv = nn.Conv2d(bn_chan, n_src * bn_chan, 1)
          self.first_out = nn.Sequential(nn.PReLU(), net_out_conv)
          # Gating and masking in 2D space (after fold)
          self.net_out = nn.Sequential(nn.Conv1d(bn_chan, bn_chan, 1), nn.Tanh())
          self.net_gate = nn.Sequential(nn.Conv1d(bn_chan, bn_chan, 1), nn.Sigmoid())
          self.mask_net = nn.Conv1d(bn_chan, out_chan, 1, bias=False)
  
          # Get activation function.
          mask_nl_class = activations.get(mask_act)
          # For softmax, feed the source dimension.
          if has_arg(mask_nl_class, "dim"):
              self.output_act = mask_nl_class(dim=1)
          else:
              self.output_act = mask_nl_class()
  
      def forward(self, mixture_w):
          """
          Args:
              mixture_w (:class:`torch.Tensor`): Tensor of shape
                  [batch, n_filters, n_frames]
          Returns:
              :class:`torch.Tensor`
                  estimated mask of shape [batch, n_src, n_filters, n_frames]
          """
          batch, n_filters, n_frames = mixture_w.size()
          output = self.bottleneck(mixture_w)  # [batch, bn_chan, n_frames]
          output = unfold(
              output.unsqueeze(-1),
              kernel_size=(self.chunk_size, 1),
              padding=(self.chunk_size, 0),
              stride=(self.hop_size, 1),
          )
          n_chunks = output.size(-1)
          output = output.reshape(batch, self.bn_chan, self.chunk_size, n_chunks)
          # Apply stacked DPRNN Blocks sequentially
          output = self.net(output)
          # Map to sources with kind of 2D masks
          output = self.first_out(output)
          output = output.reshape(batch * self.n_src, self.bn_chan, self.chunk_size, n_chunks)
          # Overlap and add:
          # [batch, out_chan, chunk_size, n_chunks] -> [batch, out_chan, n_frames]
          to_unfold = self.bn_chan * self.chunk_size
          output = fold(
              output.reshape(batch * self.n_src, to_unfold, n_chunks),
              (n_frames, 1),
              kernel_size=(self.chunk_size, 1),
              padding=(self.chunk_size, 0),
              stride=(self.hop_size, 1),
          )
          # Apply gating
          output = output.reshape(batch * self.n_src, self.bn_chan, -1)
          output = self.net_out(output) * self.net_gate(output)
          # Compute mask
          score = self.mask_net(output)
          est_mask = self.output_act(score)
          est_mask = est_mask.view(batch, self.n_src, self.out_chan, n_frames)
          return est_mask
  
      def get_config(self):
          config = {
              "in_chan": self.in_chan,
              "out_chan": self.out_chan,
              "bn_chan": self.bn_chan,
              "hid_size": self.hid_size,
              "chunk_size": self.chunk_size,
              "hop_size": self.hop_size,
              "n_repeats": self.n_repeats,
              "n_src": self.n_src,
              "norm_type": self.norm_type,
              "mask_act": self.mask_act,
              "bidirectional": self.bidirectional,
              "rnn_type": self.rnn_type,
              "num_layers": self.num_layers,
              "dropout": self.dropout,
          }
          return config
  
  
  class LSTMMasker(nn.Module):
      """ LSTM mask network introduced in [1], without skip connections.
  
      Args:
          in_chan (int): Number of input filters.
          n_src (int): Number of masks to estimate.
          out_chan  (int or None): Number of bins in the estimated masks.
              Defaults to `in_chan`.
          rnn_type (str, optional): Type of RNN used. Choose between ``'RNN'``,
              ``'LSTM'`` and ``'GRU'``.
          n_layers (int, optional): Number of layers in each RNN.
          hid_size (int): Number of neurons in the RNNs cell state.
          mask_act (str, optional): Which non-linear function to generate mask.
          bidirectional (bool, optional): Whether to use BiLSTM
          dropout (float, optional): Dropout ratio, must be in [0,1].
  
      References:
          [1]: Yi Luo et al. "Real-time Single-channel Dereverberation and Separation
              with Time-domain Audio Separation Network", Interspeech 2018
      """
  
      def __init__(
          self,
          in_chan,
          n_src,
          out_chan=None,
          rnn_type="lstm",
          n_layers=4,
          hid_size=512,
          dropout=0.3,
          mask_act="sigmoid",
          bidirectional=True,
      ):
          super().__init__()
          self.in_chan = in_chan
          self.n_src = n_src
          out_chan = out_chan if out_chan is not None else in_chan
          self.out_chan = out_chan
          self.rnn_type = rnn_type
          self.n_layers = n_layers
          self.hid_size = hid_size
          self.dropout = dropout
          self.mask_act = mask_act
          self.bidirectional = bidirectional
  
          # Get activation function.
          mask_nl_class = activations.get(mask_act)
          # For softmax, feed the source dimension.
          if has_arg(mask_nl_class, "dim"):
              self.output_act = mask_nl_class(dim=1)
          else:
              self.output_act = mask_nl_class()
  
          # Create TasNet masker
          out_size = hid_size * (int(bidirectional) + 1)
          if bidirectional:
              self.bn_layer = GlobLN(in_chan)
          else:
              self.bn_layer = CumLN(in_chan)
          self.masker = nn.Sequential(
              SingleRNN(
                  "lstm",
                  in_chan,
                  hidden_size=hid_size,
                  n_layers=n_layers,
                  bidirectional=bidirectional,
                  dropout=dropout,
              ),
              nn.Linear(out_size, self.n_src * out_chan),
              self.output_act,
          )
  
      def forward(self, x):
          batch_size = x.shape[0]
          to_sep = self.bn_layer(x)
          est_masks = self.masker(to_sep.transpose(-1, -2)).transpose(-1, -2)
          est_masks = est_masks.view(batch_size, self.n_src, self.out_chan, -1)
          return est_masks
  
      def get_config(self):
          config = {
              "in_chan": self.in_chan,
              "n_src": self.n_src,
              "out_chan": self.out_chan,
              "rnn_type": self.rnn_type,
              "n_layers": self.n_layers,
              "hid_size": self.hid_size,
              "dropout": self.dropout,
              "mask_act": self.mask_act,
              "bidirectional": self.bidirectional,
          }
          return config
  
apis: torch.nn.Linear torch.nn.PReLU torch.nn.Tanh torch.nn.Conv1d torch.nn.ModuleList torch.nn.Conv2d torch.nn.Sequential torch.nn.Sigmoid torch.cat torch.nn.Dropout