I'll admit it, I never really got the yield statement in C# before today. However there's a very good article I've just read on msdn that takes you through it step-by-step. It's certainly an interesting read and with luck will help you out when you really really need it.

Have a look...
http://msdn2.microsoft.com/en-us/vcsharp/bb264519.aspx

On an aside, what is it about developers that find it so hard to admit ignorance? Ignorance isn't the same as stupidity so why be worried about showing it. They tend to bluster and crow until you finally realise they're not sure of what they're saying. I suppose it's a common thing in a job where the amount you know is pretty much equal to the amount you're respected by your peers.

It's like if I'm talking to people who are non-developers they say something like 'Ohhhh you're so clever being a developer, I could never do that'. Why not? I've been playing with computers since my dad bought a BBC Model B when I was 5. Heck! I could count in hex at the age of 5 because that was how the programs loaded from tape. I've had 4 years of degree and many years of experience programming. So it's not like I didn't have a lot of experience and training to get where I am today. I generally wouldn't have the first clue of how to do their jobs so why would they expect they could do mine without similar training? Developers are not inherently more intelligent that other people they're just better trained in talking to very high speed morons (computers - just in care you're confused).