Function instance_of 

pub(crate) fn instance_of(
    world: &mut World,
    mesh: RenderEntity,
    material: RenderEntity,
    transform: Transform,
) -> RenderEntity

Spawn one rendered instance from asset entities, answering the new entity.

This is the instance a job that builds several things in one step spawns for itself. Panics when the world carries no MeshSource, or when an asset entity is gone.