Macro once_chain 

macro_rules! once_chain {
    (
        $first:expr
        $(
            , $second:expr
        )* $(,)?
    ) => { ... };
}

Macro to not repeat yourself writing once(...).chain(once(...))

Allows usage of calling one at a time:

once_chain!((&self.escape, "escape"))

or multiple at a time to even save repeated once_chain! invocations:

once_chain! {
    (&self.escape, "escape"),
    (&self.quit, "quit"),
}