/**
* combines the base type content model and this content model
*/
protected Expression combineToBaseType( ComplexTypeExp baseType, Expression addedExp ) {
if( extension ) {
SuperClassItem si = new SuperClassItem(baseType.body);
reader.setDeclaredLocationOf(si);
return reader.pool.createSequence( si, addedExp );
} else
// what shall we do if it's a restriciton.
return addedExp;