template <typename T>
alt_opt<T&> foo()
{
...

    if(x)
    {
        /* Application of F.1.b */
        T & t1 = p1();
        //use t1
    
        /* Application of F.1.b */
        T & t2 = p2();
        //use t2
    
        /* Application of F.1.a */
        alt_opt<T&> o(q1());
        //Do 1
    
        //Application of F.2.a */
        return bar1(o, other_relevant_parameters_here);
    }
    
    if(y)
    {
        /* Application of F.1.a */
        alt_opt<T&> o(q2());
        //Do 2
    
        //Application of F.2.a */
        return bar1(o, other_relevant_parameters_here);
    }
}

/* Application of F.2.b */
template <typename T>
alt_opt<T&> bar1(o, other_relevant_parameters_here)
{

    //Do 3: use o here ...

    switch(cond)
    {
        case a:
        {
            /* Application of F.1.a */
            alt_opt<T&> o1(foo1());
    
            //Application of F.2.a */
            return bar2(o1, other_relevant_parameters_here);
        }
        case b:
        {
            /* Application of F.1.a */
            alt_opt<T&> o1(foo2());
    
            //Application of F.2.a */
            return bar2(o1, other_relevant_parameters_here);
        }
        
        //likewise for c,d,e
    
        default:
        {
            /* Application of F.1.a */
            alt_opt<T&> o1;
    
            //Application of F.2.a */
            return bar2(o1, other_relevant_parameters_here);
        }
    }
}

/* Application of F.2.b */
template <typename T>
alt_opt<T&> bar2(o, other_relevant_parameters_here)
{
    if(o)
    {
        //Do 4.
    }

    /* Application of F.1.a */
    alt_opt<T&> o1(foo8());

    //Application of F.2.a */
    return bar3(o1, other_relevant_parameters_here);
}

/* Application of F.2.b */
template <typename T>
alt_opt<T&> bar3(o, other_relevant_parameters_here)
{
    //Do 5.
    
    return o1;
}