def key_from_val(dictionary: dict, value) -> str:
    """
    Helper method - get dictionary key corresponding to (unique) value.

    :param dict dictionary: dictionary
    :param object value: unique dictionary value
    :return: dictionary key
    :rtype: str
    :raises: KeyError: if no key found for value

    """

    val = None
    for key, val in dictionary.items():
        if val == value:
            return key
    raise KeyError(f"No key found for value {value}")