Function compile 

pub fn compile(
    src: &str,
    run: &Run,
    profile: Profile,
    caps: &str,
) -> Result<Compiled, String>

Compile src for the engine: lower run and prove it ≡ VM (lower_main / lower), check the image against the engine profile and the flashed image’s caps (NAME=N,…, DEPTH and HEAP measured on the exact arguments), then emit the wire image and the bytecode it was lowered from. A refusal is the sentence a person reads on the screen.