docstr: `sox_io_backend.save` can save audio with many channels
docstr_tok: ["`","sox_io_backend.save","`","can","save","audio","with","many","channels"]
code: def test_save_multi_channels(self, num_channels):
      """`sox_io_backend.save` can save audio with many channels"""
      self.assert_save_consistency(
          "wav",
          encoding="PCM_S",
          bits_per_sample=16,
          num_channels=num_channels,
      )
  
imports: import os
  import torch
  from parameterized import parameterized
  from torchaudio.backend import sox_io_backend
  from torchaudio_unittest.common_utils import get_wav_data, load_wav, nested_params, PytorchTestCase, save_wav, skipIfNoExec, skipIfNoSox, skipIfNoSoxEncoder, sox_utils, TempDirMixin, TorchaudioTestCase
  from .common import get_enc_params, name_func
label_desc: Use image node_id 13 for calling the SaveTest obj's underlying member method code with example usage: obj.test_save_multi_channels(num_channels) without return types