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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 one_hot2string(arr, vocab):
 """Convert a one-hot encoded array back to string """

    tokens = one_hot2token(arr)
    indexToLetter = _get_index_dict(vocab)

    return [''.join([indexToLetter[x] for x in row]) for row in tokens]