code: function parseDashArgs (args, parsed) {
    let arg = args[0];
  
    if (arg[0] === "-") {
      parsed.args.push(args.shift());
      return true;
    }
  }
docs: If the current argument starts with - or --,
  then this function shifts it to {@link ParsedArgs#args}.
  
  @param {string[]} args - The command-line arguments that have not yet been parsed
  @param {ParsedArgs} parsed - The command-line arguments that have already been parsed
  @returns {boolean}