def METHOD_NAME(self, number):
    """
    starting here, it groups the number by three from the tail
    '1234567' -> (('1',),('234',),('567',))
    :param number:str
    :rtype:tuple
    """
    blocks = ()
    length = len(number)
    if length < 3:
        blocks += ((number,),)
    else:
        len_of_first_block = length % 3
        if len_of_first_block > 0:
            first_block = number[0:len_of_first_block],
            blocks += first_block,
        for i in range(len_of_first_block, length, 3):
            next_block = (number[i:i + 3],),
            blocks += next_block
    return blocks