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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 _display_interval(i):
 """Convert a time interval into a human-readable string. :param i: The interval to convert, in seconds. """

    sigils = ["d", "h", "m", "s"]
    factors = [24 * 60 * 60, 60 * 60, 60, 1]
    remain = int(i)
    result = ""
    for fac, sig in zip(factors, sigils):
        if remain < fac:
            continue
        result += "{}{}".format(remain // fac, sig)
        remain = remain % fac
    return result