See the clap-wide CONTRIBUTING.md. This will contain clap_derive specific notes.
__clap_ to minimize clashes with the user's variables, see #2934.clap over ::clap to allow users to re-export clap, see #2258.macro_rules, see #2823.::std::result::Result and ::std::option::Option, see #3092.#quoted #variables.#![doc(alias = "")] should also be added, see #4984