code: def mel_to_hz(mels: torch.Tensor):
      """
      Converts a Tensor of mel scaled frequencies to Hertz.
      Uses the simple formula by O'Shaughnessy (1987).
  
      Args:
          mels (torch.Tensor): mel frequencies to convert.
      """
      return 700 * (10 ** (mels / 2595) - 1)
  
file_path: julius/julius/core.py
imports: import math
  import typing
  import torch
  from torch.nn import functional
label_desc: Use image node_id 4 for calling a global function with example usage: mel_to_hz(mels) and returns: unknown