def leadingzero(number, minlength):
    """
    Add leading zeros to a number.

    :type number: number
    :param number: The number to add the leading zeros to.

    :type minlength: integer
    :param minlength: If the number is shorter than this length than add leading zeros to make the length correct.

    :return: The number with a leading zero
    :rtype: string

    >>> leadingzero(1, 2)
    '01'
    """

    # Return the number as a string with the filled number
    return str(number).zfill(int(minlength))