code: def get_dst(self, path):
      if not self.test_fileobj:
          return path
      if self.src is not None:
          raise ValueError("get_dst can be called only once.")
  
      self.src = open(path, "wb")
      return self.src
  
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 2 for calling the _MediaSourceMixin obj's underlying member method code with example usage: obj.get_dst(path) and returns: self, path