code: function exp(cmd, confdir) {
    return function (files, opt) {
      var defaultOpt = {
        cwd: process.cwd()
      };
      opt = append(defaultOpt, opt);
  
      if (typeof files == 'string')
        files = [ files ];
  
      require(path.resolve(confdir, cmd + '.js'))(files, opt);
    };
  }
docs: exports a command