An event listener associates a callback function with a specific event.
system.events.EventListener interface is the primary method for handling events. Users implement the
system.events.EventListener interface and register their listener on an
system.events.IEventDispatcher using the
addEventListener. The users should also remove their
system.events.EventListener from its
system.events.IEventDispatcher after they have completed using the listener.
This method is called whenever an event occurs of the type for which the EventListener interface was registered.
Returns the string representation of this instance.
the string representation of this instance.