class_docstr: Envelope Variance Channel Selection method with
  (optionally) learnable per mel-band weights.
code: def _count_chunks(self, inlen, chunk_size, chunk_stride):
      return int((inlen - chunk_size + chunk_stride) / chunk_stride)
  
imports: import argparse
  import os
  from copy import deepcopy
  from pathlib import Path
  import lhotse
  import soundfile
  import torch
  import torchaudio
  import tqdm
  from torch.utils.data import DataLoader, Dataset
label_desc: Use image node_id 3 for calling the EnvelopeVariance obj's underlying member method code with example usage: obj._count_chunks(inlen, chunk_size, chunk_stride) and returns: int