Macro embed 

macro_rules! embed {
    ($folder:literal, [$($name:literal),+ $(,)?]) => { ... };
    ($path:expr, compiled = $compiled:expr) => { ... };
    ($path:expr) => { ... };
}

A file by its path from the calling crate’s root, the path a development build rereads; compiled = embeds what the build script wrote to OUT_DIR from it instead, and embed!("folder", [names]) gives a &[File].