we need a class that inherits two other classes. But there is a big
difficulty, so I describe a little further. There are two classes let us
call them C1 and C2. C1 is inherited by A1, C2 by A2. Both classes (A1 and
A2) need more methods, which lay in another class (let us say Z). Therefore
A1 inherits C1 and Z, A2 inherits C2 and Z, but Z does _not_ inherit any
other class, even because they are different. We use VO 2.5b-1. Is this
possible and if yes, how can we implement it?