code: def extract_native_client_tarball(dir):
      r'''
      Download a native_client.tar.xz file from TaskCluster and extract it to dir.
      '''
      assert_valid_dir(dir)
  
      target_tarball = os.path.join(dir, 'native_client.tar.xz')
      if os.path.isfile(target_tarball) and os.stat(target_tarball).st_size == 0:
          return
  
      subprocess.check_call(['pixz', '-d', 'native_client.tar.xz'], cwd=dir)
      subprocess.check_call(['tar', 'xf', 'native_client.tar'], cwd=dir)
      os.unlink(os.path.join(dir, 'native_client.tar'))
      open(target_tarball, 'w').close(f extract_native_client_tarball(dir):
      r'''
      Download a native_client.tar.xz file from TaskCluster and extract it to dir.
      '''
      assert_valid_dir(dir)
  
      target_tarball = os.path.join(dir, 'native_client.tar.xz')
      if os.path.isfile(target_tarball) and os.stat(target_tarball).st_size == 0:
          return
  
      subprocess.check_call(['pixz', '-d', 'native_client.tar.xz'], cwd=dir)
      subprocess.check_call(['tar', 'xf', 'native_client.tar'], cwd=dir)
      os.unlink(os.path.join(dir, 'native_client.tar'))
      open(target_tarball, 'w').close()
docs: r'''
      Download a native_client.tar.xz file from TaskCluster and extract it to dir.