for (UnboundRule rule : rules) {
            writer.print(prefix);
            writer.println(rule.getDescriptor());
            if (rule.getMutableInputs().size() > 0) {
                heading("subject:");
                reportInputs(rule.getMutableInputs());
            }
            if (rule.getImmutableInputs().size() > 0) {
                heading("inputs:");
                reportInputs(rule.getImmutableInputs());

        return descriptor;
    }

    public List<? extends UnboundRuleInput> getImmutableInputs() {
        return immutableInputs;
    }

    public List<? extends UnboundRuleInput> getMutableInputs() {
        return mutableInputs;
    }

    public static Builder descriptor(String descriptor) {
        return new Builder(descriptor);
    }