Function bevy::ecs::system::assert_is_read_only_system

pub fn assert_is_read_only_system<In, Out, Marker, S>(sys: S)where
    S: IntoSystem<In, Out, Marker>,
    <S as IntoSystem<In, Out, Marker>>::System: ReadOnlySystem,

Ensure that a given function is a read-only system.

This should be used when writing doc examples, to confirm that systems used in an example are valid systems.