I have three class , called `A`,`B`,`C` and another class called `X`.

In this `X` class I want to access a few function from `A`, `B` and `C`.

I know if I want to access the function in one class, I can use:

```
class X extends A { ... }

```

Now I can access all `A` public functions, but now I want to access the `B` and `C` class functions as well.

How do I access methods from `B` and `C` from within `X`?