Macro acs 

macro_rules! acs {
    ( $( $x:expr ),* $(,)? ) => { ... };
}

Example

    use matchmaker::{action::{Action, Actions, acs}, render::MMState};
    pub fn fsaction_aliaser(
        a: Action,
        state: &MMState<'_, '_, String, String>,
    ) -> Actions {
        match a {
            Action::Custom(_) => {
              log::debug!("Ignoring custom action");
              acs![]
            }
            _ => acs![a], // no change
        }
    }