code: function flag(argv, arg) {
      var value = false
        , i
        , key
        , opt
        , chars;
      arg = arg.replace(/^-/, '');
      //console.dir('flag: ' + arg);
      for(i = 0;i < names.length;i++) {
        key = names[i];
        if(!flags[key]) {
          continue;
        }
        opt = option[key].replace(/^-/, '');
        if(arg === opt) {
          return key;
        }
      }
  
      // handle flag expansion
      chars = arg.split('');
      while((arg = chars.shift())) {
        if((short + arg === option.always) && flags.always) {
          value = always;
        }else if((short + arg === option.never) && flags.never) {
          value = never;
        }
      }
      return value;
    }
docs: parse flags