code: def test_encoder_backward(whisper_encoder):
      whisper_encoder.train()
      input_tensor = torch.randn(
          4, 3200, device=next(whisper_encoder.parameters()).device
      )
      xs_pad, _, _ = whisper_encoder(input_tensor, None)
  
      xs_pad.sum().backward()
  
file_path: espnet/test/espnet2/asr/encoder/test_whisper_encoder.py
imports: import sys
  import pytest
  import torch
  from packaging.version import parse
  from espnet2.asr.encoder.whisper_encoder import OpenAIWhisperEncoder
label_desc: Use image node_id 6 for calling a global function with example usage: test_encoder_backward(whisper_encoder) without return types