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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def tar_and_copy_t2t(train_dir):
 """Tar Tensor2Tensor and cp to train_dir."""

  tf.logging.info("Tarring and pushing local Tensor2Tensor package.")

  output = text_encoder.native_to_unicode(shell_output(
      "pip show tensor2tensor")).split("\n")
  assert output[1].startswith("Version")
  assert output[7].startswith("Location")
  t2t_version = output[1].split(":")[1].strip()
  t2t_dir = output[7].split(":")[1].strip()

  # A local installation cloned from GitHub will have a setup.py file and a docs
  # folder
  is_local_t2t = all([
      tf.gfile.Exists(os.path.join(t2t_dir, fname))
      for fname in ["setup.py", "docs/cloud_mlengine.md"]
  ])

  if is_local_t2t:
    tf.logging.info("Found local T2T installation. Tarring directory %s",
                    t2t_dir)
  else:
    # PyPI installation
    # Create a folder with just a setup.py file pointing to the right version
    tf.logging.info("Found PyPI T2T installation. Launching tensor2tensor==%s",
                    t2t_version)
    t2t_dir = os.path.join(tempfile.gettempdir(), "tensor2tensor_tmp")
    shutil.rmtree(t2t_dir, ignore_errors=True)
    os.mkdir(t2t_dir)
    setup_fname = os.path.join(t2t_dir, "setup.py")
    setup_file_str = get_setup_file(
        name="DummyT2TPackage",
        packages=["tensor2tensor==%s" % t2t_version]
    )
    with tf.gfile.Open(setup_fname, "w") as f:
      f.write(setup_file_str)
  t2t_tar = _tar_and_copy(t2t_dir, train_dir)
  return t2t_tar