/*
  * (non-Javadoc)
  *
  * @see org.eclipse.gef.commands.Command#execute()
  */
 @Override
 public void execute() {
   Context context = CorePlugin.getContext();
   if (context.getBreakpointNodes(process).contains(node)) {
     context.removeBreakpoint(process, node);
   } else {
     context.addBreakpoint(process, node);
   }
 }