code: func (v *Entry) GetCompletion() (*EntryCompletion, error) {
  	c := C.gtk_entry_get_completion(v.native())
  	if c == nil {
  		return nil, nilPtrErr
  	}
  
  	e := &EntryCompletion{glib.Take(unsafe.Pointer(c))}
  	return e, nil
  }
docs: // GetCompletion() is a wrapper around gtk_entry_get_completion().