$ 04_02_parse --help clap [..] A simple to use, efficient, and full-featured Command Line Argument Parser USAGE: 04_02_parse[EXE] <PORT> ARGS: <PORT> Network port to use OPTIONS: -h, --help Print help information -V, --version Print version information $ 04_02_parse 22 PORT = 22 $ 04_02_parse foobar ? failed error: Invalid value "foobar" for '<PORT>': invalid digit found in string For more information try --help $ 04_02_parse_derive 0 ? failed error: Invalid value "0" for '<PORT>': 0 is not in 1..=65535 For more information try --help