#!/usr/bin/env python


from math import log2
from qas_flow import Stream


def gen():
    n = 0
    while True:
        yield n
        n += 1


def mapfunc(ix):
    i, x = ix
    return str(x) * int(log2(i + 1))


strm = Stream(gen())
print(strm.enumerate().map(mapfunc).skip(20).take(4).enumerate().collect())