Go subtleties

Ah the old nil values boxed into non-nil interfaces. Even after 8 years writing go code almost every day this still bites me occasionally. I've never seen code that actually uses this. I understand why it is the way it is but I hate it.

The advice I've read (and follow) is always to return values, not interfaces, from functions and test for nil against them. That IME tends to nip the majority of nil interface problems in the bud.