Meet VETO: The VETO-in-NULL-out Protocol

[hostilefork]

@hostilefork

    keep opt compose ~[
        return: (conditional ret.spec)
    ]~

I'll point this out as an interesting--although misguided---use of ~(veto)~

It implements the same intent as:

if ret.spec [
    keep compose ~[
        return: (ret.spec)
    ]~
]

But it's clearer with the IF... and also avoids unnecessary computation (why call COMPOSE at all, and have it start building a stack it's going to throw away?)

So I'm going to change it...

..BUT sometimes you just want the code to be structured differently. If I were in a situation where adding control outside would be disruptive, I can put the control inside. Cool to have that ability.