code: func removeClosure(_ C.gpointer, closure *C.GClosure) {
  	closures.Lock()
  	delete(closures.m, closure)
  	closures.Unlock()
  }
docs: // removeClosure removes a closure from the internal closures map.  This is
  // needed to prevent a leak where Go code can access the closure context
  // (along with rf and userdata) even after an object has been destroyed and
  // the GClosure is invalidated and will never run.
  //
  //export removeClosure