docs: function notifyKeyspaceEvents(val) {
    var i, c;
    if(val) {
      for(i = 0;i < val.length;i++) {
        c = val.charAt(i);
        if(!~KEYSPACES_EVENTS.indexOf(c)) {
          throw new Error('Invalid event class character. Use \'g$lshzxeA\'.');
        }
      }
    }
  }