code: def tearDown(self):
      if self.src is not None:
          self.src.flush()
          self.src.close()
      super().tearDown()
  
imports: import io
  import math
  import torch
  import torchaudio
  from parameterized import parameterized, parameterized_class
  from torchaudio.io import CodecConfig, StreamReader, StreamWriter
  from torchaudio_unittest.common_utils import get_asset_path, get_sinusoid, nested_params, rgb_to_yuv_ccir, skipIfNoFFmpeg, skipIfNoModule, TempDirMixin, TorchaudioTestCase
  from .common import lt42
label_desc: Use image node_id 3 for calling the _MediaSourceMixin obj's underlying member method code with example usage: obj.tearDown() without return types