docs: function getListeners(obj, eventName) {
      var listenerDesc = Object.getOwnPropertyDescriptor(obj, '__jahEventListeners__')
      if (!listenerDesc) {
          Object.defineProperty(obj, '__jahEventListeners__', {
              value: {}
          })
      }
      if (!eventName) {
          return obj.__jahEventListeners__;
      }
      if (!obj.__jahEventListeners__[eventName]) {
          obj.__jahEventListeners__[eventName] = {};
      }
      return obj.__jahEventListeners__[eventName];
  }