Trait Guard
viz_core
pub trait Guard: Send + Sync + 'static { fn check(&self, _: &Context) -> bool; }
fn check(&self, _: &Context) -> bool
impl Guard for Box<dyn Guard>
fn check(&self, cx: &Context) -> bool
impl<F> Guard for F where F: Send + Sync + 'static + Fn(&Context) -> bool,