add ( HANDLES )
           Add the list of handles to the "IO::Select" object. It is these values that will be returned when an event occurs. "IO::Select" keeps these values in a cache which is indexed by the "fileno" of the handle, so if more than one handle with the same "fileno" is specified then only the last one is cached.

           Each handle can be an "IO::Handle" object, an integer or an array reference where the first element is an "IO::Handle" or an integer.