isTrueish

[GammaGames]

Fixes #254

[jgonggrijp]

Thanks! In #254 (comment) you asked whether util.strings was the right place. I don't have strong opinions on the matter, but it seems like this function might feel more at home in function.predicates.

[jgonggrijp]

Ugh, the CI fails because of a linter rule: it doesn't like !!+v because the use of the ! operator is considered confusing.

Can you reproduce this locally, and if so, could you try to fix it? If changing the expression to !!(+v) silences the warning, I would prefer that, but I can also live with disabling this particular rule.

Otherwise, I will try to fiddle with it sometime soon.