class SkipObject:
    def __init__(self, wrapped):                  # Save item to be used
        self.wrapped = wrapped

    def __iter__(self):
        return SkipIterator(self.wrapped)         # New iterator each time

class SkipIterator:
    def __init__(self, wrapped):
        self.wrapped = wrapped                    # Iterator state information
        self.offset  = 0

    def __next__(self):
        if self.offset >= len(self.wrapped):      # Terminate iterations
            raise StopIteration
        else:
            item = self.wrapped[self.offset]      # else return and skip
            self.offset += 2
            return item

if __name__ == '__main__':
    alpha = 'abcdef'
    skipper = SkipObject(alpha)                   # Make container object
    I = iter(skipper)                             # Make an iterator on it
    print(next(I), next(I), next(I))              # Visit offsets 0, 2, 4

    for x in skipper:                # for calls __iter__ automatically
        for y in skipper:            # Nested fors call __iter__ again each time
            print(x + y, end=' ')    # Each iterator has its own state, offset