float CallbackChain_ReturnValue; // read-only field of the current return value
entity CallbackChain_New(string name);
-float CallbackChain_Add(entity cb, float() func, float order)
+float CallbackChain_Add(entity cb, float() func, float order);
float CallbackChain_Remove(entity cb, float() func);
// a callback function is like this:
// float mycallback(entity me)