code: def _compute_start_end_frames(self, offset, duration):
      start_frame = int(self.sample_rate * offset // self.hop_len)
      end_frame = 1 + int(
          self.sample_rate * (offset + duration) // self.hop_len
      )
      return start_frame, end_frame
  
imports: import contextlib
  import tempfile
  from pathlib import Path
  import numpy
  import pytest
  import soundfile
  import torch
  from nemo.collections.tts.parts.preprocessing.features import EnergyFeaturizer, MelSpectrogramFeaturizer, PitchFeaturizer
label_desc: Use image node_id 2 for calling the TestTTSFeatures obj's underlying member method code with example usage: obj._compute_start_end_frames(offset, duration) and returns: start_frame,  end_frame