def convert_dict_keys_to_strings(dictionary):
    """
    Convert all the keys of the dictionary to strings,
    no matter which type they are.

    :param dictionary: dict()
    :return: dict() with converted keys
    """
    res = dict()
    for p in dictionary:
        if isinstance(dictionary[p], dict):
            res[str(p)] = convert_dict_keys_to_strings(dictionary[p])
        else:
            res[str(p)] = dictionary[p]
    return res