可能重复：
Can I implement yield return for IEnumerable functions in VB.NET?
如何将此Python代码转换为VB？在visual basic中有任何yield方法吗？请帮帮我。
def f(x, y):
for nx in range(max(0, x-1), min(3, x+2)):
for ny in range(max(0, y-1), min(3, y+2)):
yield (nx, ny)