Method append

src/react/properties.py:70–74

(self, item: _T)

        self._observers.remove(observer)

    def append(self, item: _T) -> None:
        super().append(item)

        for observer in self._observers:
            observer.on_add(item, len(self.data) - 1)

    def insert(self, i: int, item: _T) -> None:
        super().insert(i, item)