docstr: Forward function
  
  Args:
      x: (B, L, ...)
      ilens: (B,)
docstr_tok: ["Forward","function","Args",":","x",":","(","B",",","L",",","...",")","ilens",":","(","B",",",")"]
code: def forward(
      self, x: torch.Tensor, ilens: torch.Tensor = None
  ) -> Tuple[torch.Tensor, torch.Tensor]:
      """Forward function
  
      Args:
          x: (B, L, ...)
          ilens: (B,)
  
      """
      return utterance_mvn(
          x,
          ilens,
          norm_means=self.norm_means,
          norm_vars=self.norm_vars,
          eps=self.eps,
      )
  
file_path: espnet/espnet2/layers/utterance_mvn.py
imports: from typing import Tuple
  import torch
  from typeguard import check_argument_types
  from espnet2.layers.abs_normalize import AbsNormalize
  from espnet.nets.pytorch_backend.nets_utils import make_pad_mask
label_desc: Use image node_id 3 for calling the UtteranceMVN obj's underlying member method code with example usage: obj.forward(x, ilens) and returns: utterance_mvn