Inheritance can be implemented as well:

    typedef struct AdvancedFoo {
      BaseFoo super;
      int a, b, c;
      thinkfunc_t thinkHarder;
    } AdvancedFoo;

Since `super` is the first member in the struct, a pointer to an AdvancedFoo can be used as a pointer to BaseFoo as well:

    AdvancedFoo *advFoo = AdvancedFoo_new();
    advFoo->thinkHarder(advFoo, advFoo->a);

    ((BaseFoo*) advFoo)->doThink(advFoo, some_int_method());

Of course, this inheritance pattern can continue in multiple steps.