Method extend

src/react/properties.py:105–112

(self, other: Iterable[_T])

                observer.on_remove(item)

    def extend(self, other: Iterable[_T]) -> None:
        first_index = len(self.data)

        super().extend(other)

        for i, item in enumerate(other):
            for observer in self._observers:
                observer.on_add(item, first_index + i)


class ObservableDict(UserDict):