public static Type function(Type innerTypeA, Type innerTypeB) {
        return SimpleParameterizedType.create(Function.class, innerTypeA, innerTypeB);
    }
Generates a {@link Type} to represent a java standard {@link Function} 
with generic type variables.

@param innerTypeA  the first type variable
@param innerTypeB  the second type variable
@return            the resulting type
common-parent/codegen/src/main/java/com/speedment/common/codegen/constant/DefaultType.java