#can't change the body of this function
def positive_integers_generator():
    n = 1
    while True:
        x = yield n
        if x is not None:
            n = x
        else:
            n += 1

def change_generator(generator, n):
  for i in generator():
    if i%2 == 0:
      yield(i)

g = positive_integers_generator()

# should print 1, 2, 4
for _ in range(5):
  n = next(g)
  print(n)
  change_generator(g, n)