使用迭代器模式返回不兼容类型的2D数组

# 迭代器接口
class Iterator:
    def has_next(self):
        pass
    
    def next(self):
        pass

# 2D数组迭代器
class Array2DIterator(Iterator):
    def __init__(self, array):
        self.array = array
        self.row = 0
        self.col = 0
    
    def has_next(self):
        return self.row < len(self.array) and self.col < len(self.array[self.row])
    
    def next(self):
        value = self.array[self.row][self.col]
        self.col += 1
        if self.col >= len(self.array[self.row]):
            self.row += 1
            self.col = 0
        return value

# 客户端代码
def main():
    array = [[1, 2, 3], [4, 5], [6, 7, 8, 9]]
    iterator = Array2DIterator(array)
    
    while iterator.has_next():
        print(iterator.next())

if __name__ == '__main__':
    main()