//! How to add `no-thing` flag which is `true` by default and
//! `false` if passed.
//!
//! Running this example with --help prints this message:
//! -----------------------------------------------------
//! structopt 0.3.25
//!
//! USAGE:
//! negative_flag [FLAGS]
//!
//! FLAGS:
//! -h, --help Prints help information
//! -V, --version Prints version information
//! --no-verbose
//! -----------------------------------------------------
use StructOpt;