dispose method
      
void
dispose()
      
     
    
    
Implementation
void dispose() {
  if (_disposed) return;
  _disposed = true;
  clearPending();
  _handlers.clear();
  _apiHandlers.clear();
  _resultController.close();
}
void dispose() {
  if (_disposed) return;
  _disposed = true;
  clearPending();
  _handlers.clear();
  _apiHandlers.clear();
  _resultController.close();
}