Custom commands in Bevy with extension traits

Bevy is an ECS-based game engine built in Rust. Extension traits are a pattern in rust that allows you to add methods to an existing type defined outside of your crate. You can probably guess where I’m going with this. In bevy, any system can access the Commands structure to issue commands manipulate the World. The most common one would probably be the Commands#spawn method which lets you spawn an entity with the components you specify.