You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: mod.rs
    path of file: ./repos/bevy/crates/bevy_pbr/src/lightmap
    
    the code of the file until where you have to start completion: //! Lightmaps, baked lighting textures that can be applied at runtime to provide
//! diffuse global illumination.
//!
//! Bevy doesn't currently have any way to actually bake lightmaps, but they can
//! be baked in an external tool like [Blender](http://blender.org), for example
//! with an addon like [The Lightmapper]. The tools in the [
    
pub(crate) fn pack_lightmap_uv_rect(maybe_rect: Option<Rect>) -> UVec2 {
    match maybe_rect {
        Some(rect) => {
            let rect_uvec4 = (vec4(rect.min.x, rect.min.y, rect.max.x, rect.max.y) * 65535.0)
                .round()
                .as_uvec4();
            uvec2(
                rect_uvec4.x | (rect_uvec4.y << 16),
                rect_uvec4.z | (rect_uvec4.w << 16),
            )
        }
        None => UVec2::ZERO,
    }
}