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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 _brevity_penalty(ref_length, trans_length):
 """Calculate brevity penalty. Parameters ref_length: int Sum of all closest references'lengths for every translations in a corpus trans_length: int Sum of all translations's lengths in a corpus. Returns ------- bleu's brevity penalty: float """

    if trans_length > ref_length:
        return 1
    # If translation is empty, brevity penalty = 0 should result in BLEU = 0.0
    elif trans_length == 0:
        return 0
    else:
        return math.exp(1 - float(ref_length) / trans_length)