Show all template type codes that are not used by any document.
SELECT template_type_code FROM Templates EXCEPT SELECT template_type_code FROM Templates AS T1 JOIN Documents AS T2 ON T1.template_id  =  T2.template_id
SELECT template_type_code FROM Templates EXCEPT SELECT template_type_code FROM Templates AS T1 JOIN Documents AS T2 ON T1.template_id  =  T2.template_id
[{'Template_Type_Code': 'CV'}]