class IteratorWrapper:
    def __init__(self, f, iterator):
        self.f = f
        self.iterator = iterator
        self.gen = None
 
    def __iter__(self):
        self.gen = iter(self.iterator)
 
        return self
 
    def __next__(self):
        return self.f(next(self.gen))
 
 
def iter_map(f, iterator):
    return IteratorWrapper(f, iterator)
 
 
l = [1]
 
mapped = iter_map(lambda x: x * 2, l)
 
for _ in range(2):
    for a in mapped:
        print(a)
 
cmapped = map(lambda x: x * 2, l)
 
for _ in range(2):
    for a in cmapped:
        print(a)

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