@API(status = API.Status.STABLE)
        static <C> @NonNull Filter<C> contextFree(final @NonNull BiFunction<String, String, @Nullable String> function) {
            return (ctx, suggestion, input) -> function.apply(suggestion, input);
        }
Create a new context-free {@link Filter}.

@param function function
@param <C>      sender type
@return filter
cloud-core/src/main/java/org/incendo/cloud/suggestion/FilteringSuggestionProcessor.java