如下代码中如何理解：传入的实际参数，替换def中的x还是n？

def _not_divisible(n):     return lambda x: x % n > 0

def _odd_iter():     n = 1     while True:         n = n + 2 yield n def _not_divisible(n): return lambda x: x % n > 0 def primes(n): return lambda x: x % n > 0 def primes(): yield 2 it = _odd_iter() while True: n = next(it) yield n it = filter(_not_divisible(n), it) for n in primes(): if n < 1000: print(n) else: break