pub trait ObserverSystem<E, Out = ()>:
System<In = On<'static, 'static, E>, Out = Out>
+ Send
+ 'staticwhere
E: EventPattern,{ }pub trait ObserverSystem<E, Out = ()>:
System<In = On<'static, 'static, E>, Out = Out>
+ Send
+ 'staticwhere
E: EventPattern,{ }