def gfib(n):
    a = 1
    b = 1
    while a < n:
        yield a
        a, b = b, a + b

if __name__ == '__main__':
    gen = gfib(100)
    for i in range(10): 
        print(next(gen), end=' ')
    print()
    for v in gfib(20):
        print(v, end=' ')
    print()

def ifib(): 
    a = 1
    b = 1
    while True:
        yield a 
        a, b = b, a + b

if __name__ == '__main__':
    for i, v in zip(range(15), ifib()):
        print(v, end=' ')
    print()