clap/examples/tutorial_builder/01_quick.md

$ 01_quick --help
clap [..]
A simple to use, efficient, and full-featured Command Line Argument Parser

USAGE:
    01_quick[EXE] [OPTIONS] [name] [SUBCOMMAND]

ARGS:
    <name>    Optional name to operate on

OPTIONS:
    -c, --config <FILE>    Sets a custom config file
    -d, --debug...         Turn debugging information on
    -h, --help             Print help information
    -V, --version          Print version information

SUBCOMMANDS:
    test    does testing things
    help    Print this message or the help of the given subcommand(s)

By default, the program does nothing:

$ 01_quick
Debug mode is off

But you can mix and match the various features

$ 01_quick -dd test
Debug mode is on
Not printing testing lists...