from typing import Dict
from typing import Any


def add_to_dict_with_swapped_keys(old_dict: Dict[Any, Dict],
                                  new_dict: Dict[Any, Dict]) -> Dict[Any, Dict]:
    """
    Swap the keys of two nested dictionaries in a new dictionary.
    {'Key1': {'Key2': 42}} -> {'Key2': {'Key1': 42}}
    Args:
        old_dict: a nested dictionary whose keys are to be swapped
        new_dict: an initiated dictionary, does not have to be empty

    Returns:
        the new_dict with the addition of swapped keys of the old_dict
    """
    for key1, nested_dict in old_dict.items():
        for key2, value in nested_dict.items():
            new_dict.setdefault(key2, {})[key1] = value

    return new_dict