use ? in function names that return booleans

[MalloZup]

I would suggest that we start to use ? for distinguish functions/methods that return a false/true.

Like pr_triggered_by_comment? (return a boolean where we check)
and do_test (doesn't return a boolean)

[MalloZup]

https://stackoverflow.com/questions/7179016/what-is-the-purpose-of-and-at-the-end-of-method-names