迭代器模式

def solve():
    class NumberIterator:
        def __init__(____):
            self.current = start
            self.end = end
        def __iter__(____):
            return self
        def __next__(____):
            if self.current >= self.end:
                raise StopIteration
            val = self.current
            self.current += ____
            return val
    print('____'.join(str(____) for x in NumberIterator(____, ____)))