Macro code 

code!() { /* proc-macro */ }

Compile-time syntax highlighting.

Reads a source file relative to the consumer’s CARGO_MANIFEST_DIR, parses it with arborium, and expands to the resulting span tree. Pass the path as a string literal, concat!(...), or env!(...). Optionally name the language explicitly with code!("/path", "rust"); otherwise it is inferred from the file extension.