Let's do front, back, popFront, and popBack!

[dsimcha]

== Quote from Andrei Alexandrescu (SeeWebsiteForEmail at erdani.org)'s article
> I've been thinking for a while to suggest Walter to allow overloading of
> void vs. anything else return type. Making one private or undefined
> would prevent statically that people call functions and ignore error codes.
> Andrei

Who still uses error codes?  The only time I can think of that mattering is if
you're calling C functions, in which case overloading wouldn't work anyhow.  Isn't
enforcing that the caller not ignore an error condition what exceptions are for?