code: function outputPages(names, cb) {
      if (typeof names === 'function') { cb = names; names = ''; }
  
      names = u.isArray(names) ? names :
             names ? [names] :
             u.keys(opts.output$);
  
      var ab = asyncbuilder(cb);
  
      u.each(names, function(name) {
        var output = opts.output$[name];
        if (output) {
          output.output(ab.asyncAppend());
        } else {
          ab.append('outputPages called with unknown output: ' + name);
        }
      });
  
      ab.complete();
    }
docs: --//--//--//--//--//--//--//--//--// trigger specified (or all) outputs