# """
# This is the interface that allows for creating nested lists.
# You should not implement it, or speculate about its implementation
# """
# class NestedInteger:
#    def isInteger(self) -> bool:
#        """
#        @return True if this NestedInteger holds a single integer, rather than a nested list.
#        """
#
#    def getInteger(self) -> int:
#        """
#        @return the single integer that this NestedInteger holds, if it holds a single integer
#        Return None if this NestedInteger holds a nested list
#        """
#
#    def getList(self) -> [NestedInteger]:
#        """
#        @return the nested list that this NestedInteger holds, if it holds a nested list
#        Return None if this NestedInteger holds a single integer
#        """
class NestedIterator:
    def __init__(self, nestedList: [NestedInteger]):
        self.nestedList = nestedList
        self.currentIdx = 0
        self.arr = flatten(self.nestedList)

    def next(self) -> int:
        if self.hasNext():
            ans = self.arr[self.currentIdx]
            self.currentIdx += 1
            return ans
        return None

    def hasNext(self) -> bool:
        if self.currentIdx < len(self.arr):
            return True
        return False


def flatten(l):
    arr = []
    for ele in l:
        if ele.isInteger():
            arr.append(ele)
        else:
            thisFlattened = flatten(ele.getList())
            arr.extend(thisFlattened)
    return arr

# Your NestedIterator object will be instantiated and called as such:
# i, v = NestedIterator(nestedList), []
# while i.hasNext(): v.append(i.next())