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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 _build_synset_lookup(imagenet_metadata_file):
 """Build lookup for synset to human-readable label. Args: imagenet_metadata_file: string, path to file containing mapping from synset to human-readable label. Assumes each line of the file looks like: n02119247 black fox n02119359 silver fox n02119477 red fox, Vulpes fulva where each line corresponds to a unique mapping. Note that each line is formatted as <synset>\t<human readable label>. Returns: Dictionary of synset to human labels, such as: 'n02119022' --> 'red fox, Vulpes vulpes' """

  lines = tf.gfile.FastGFile(imagenet_metadata_file, 'r').readlines()
  synset_to_human = {}
  for l in lines:
    if l:
      parts = l.strip().split('\t')
      assert len(parts) == 2
      synset = parts[0]
      human = parts[1]
      synset_to_human[synset] = human
  return synset_to_human