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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 three_digit(number):
 """ Add 0s to inputs that their length is less than 3. :param number: The number to convert :type number: int :returns: String :example: '001' """

    number = str(number)
    if len(number) == 1:
        return u'00%s' % number
    elif len(number) == 2:
        return u'0%s' % number
    else:
        return number