[]=

static VALUE
wmap_aset(VALUE self, VALUE wmap, VALUE orig)
{
    struct weakmap *w;

    TypedData_Get_Struct(self, struct weakmap, &weakmap_type, w);
    should_be_finalizable(orig);
    should_be_finalizable(wmap);
    define_final0(orig, w->final);
    define_final0(wmap, w->final);
    st_update(w->obj2wmap, (st_data_t)orig, wmap_aset_update, wmap);
    st_insert(w->wmap2obj, (st_data_t)wmap, (st_data_t)orig);
    return nonspecial_obj_id(orig);
}