from typing import OrderedDict


def _sort_date_dict(date_dict):
    """
    Sort a dictionary with dates as keys in chronological order

    Args:
        :date_dict: (dict) dictionary (key must be dates in sortable format)

    Returns:
        :sorted_dict: (dict) dictionary sorted by keys
    """

    # Note: OrderedDict() should not be necessary in 3.8
    return OrderedDict({k: v for k, v in sorted(date_dict.items())})