def METHOD_NAME(
    set_id: t.Any,
    *,
    case: str = "default",
    requests_mock: responses.RequestsMock | None = None,
) -> RegisteredResponse | ResponseList:
    """
    Optionally lookup and activate an individual response. If given a
    ``RegisteredResponse``, activate it, otherwise the first argument is an ID
    of a ``ResponseSet`` used for lookup. By default, looks for the response
    registered under ``case="default"``.
    :param set_id: The ID used to retrieve the response set. Typically a string, but
        could be any key used to register a response set.
    :type set_id: any
    :param case: The name of a case within the response set to load, ignoring all other
        registered mocks in the response set
    :type case: str, optional
    :param requests_mock: A ``responses`` library mock to use for response mocking,
        defaults to the ``responses`` default
    :type requests_mock: ``responses.RequestsMock``, optional
    """
    if isinstance(set_id, RegisteredResponse):
        return set_id.add(requests_mock=requests_mock)
    rset = get_response_set(set_id)
    return rset.activate(case, requests_mock=requests_mock)