Returns the registered collection resource class for the given marker
    interface or member resource class or instance.

    :param rc: registered resource
    :type rc: class implementing or instance providing or subclass of
        a registered resource interface.

def get_collection_class(resource):
    """
    Returns the registered collection resource class for the given marker
    interface or member resource class or instance.

    :param rc: registered resource
    :type rc: class implementing or instance providing or subclass of
        a registered resource interface.
    """
    reg = get_current_registry()
    if IInterface in provided_by(resource):
        coll_class = reg.getUtility(resource, name='collection-class')
    else:
        coll_class = reg.getAdapter(resource, ICollectionResource,
                                    name='collection-class')
    return coll_class