import time
from concurrent.futures import ProcessPoolExecutor

NUMBERS = list(range(25, 38))
def fib(n):
    if n<= 2:
        return 1
    return fib(n-1) + fib(n-2)

start = time.time()
with ProcessPoolExecutor(max_workers=3) as executor:
    for num, result in zip(NUMBERS, executor.map(fib, NUMBERS)):
        print(('fib({}) = {}'.format(num, result)))
print(('COST: {}'.format(time.time() - start)))