docstr: `soundfile_backend.save` can save flac format.
docstr_tok: ["`","soundfile_backend.save","`","can","save","flac","format","."]
code: def assert_flac(self, dtype, sample_rate, num_channels):
      """`soundfile_backend.save` can save flac format."""
      self._assert_non_wav("flac", dtype, sample_rate, num_channels)
  
imports: import io
  from unittest.mock import patch
  from torchaudio._internal import module_utils
  from torchaudio.backend import soundfile_backend
  from torchaudio_unittest.common_utils import get_wav_data, load_wav, nested_params, PytorchTestCase, skipIfNoModule, TempDirMixin
  from .common import fetch_wav_subtype, parameterize, skipIfFormatNotSupported
label_desc: Use image node_id 3 for calling the SaveTestBase obj's underlying member method code with example usage: obj.assert_flac(dtype, sample_rate, num_channels) without return types