def pad_number(number, len=6):
    """
    Used for padding task id's. Takes a number and adds padding zeros
    to it. E.g. 4 => 000004 with default of length 6. 

    :param number: Number to pad.
    :type number: int
    :param len: Total length of the resulting string.
    :type len: int
    """
    return str(number).zfill(len)