nextPage method
scroll to next month / week
it will do animate while duration is not null
Implementation
nextPage({
Duration duration,
Curve curve = Curves.bounceInOut
}) {
if (duration != null) {
_pageController.nextPage(
duration: duration,
curve: curve
);
} else {
_pageController.jumpToPage((_pageController.page + 1).toInt());
}
}