from typing import Union

class PaginatedList:
    def __init__(self, data: list, page_size: int, current_page:int=0):
        self.data = data
        self.page_size = page_size
        self.current_page = current_page

    @property
    def divided_list(self):
        return [
            self.data[x : x + self.page_size]
            for x in range(0, len(self.data), self.page_size)
        ]

    def get_page(self, page: int) -> Union[list, None]:
        if page < len(self.divided_list):
            return self.divided_list[page]
        return None

    def get_current_page(self) -> list:
        return self.get_page(self.current_page)

    def page_up(self) -> Union[list, None]:
        if self.current_page + 1 < len(self.divided_list):
            self.current_page += 1
            return self.get_page(self.current_page)
        return None

    def page_down(self) -> Union[list, None]:
        if self.current_page - 1 >= 0:
            self.current_page -= 1
            return self.get_page(self.current_page)
        return None