from typing import Union
from typing import List


def dates_as_lists(end_date: Union[str, List[str]], start_date: Union[str, List[str]]):
    """
    If the given dates are pure strings convert them to lists of strings.
    Args:
        end_date (Union[str, List[str]]): End date of the data that will be selected for each building.
        start_date (List[str]): Start date of the data that will be selected for each building.
    Returns:
        Returns the start and end dates as lists of dates.
    """
    if not isinstance(start_date, list):
        start_date = [start_date]
    if not isinstance(end_date, list):
        end_date = [end_date]
    return end_date, start_date