title: Implement an interface using inheritance (child classes)
body: <p>Im trying to implement a system like the class diagram below.<br>
  I would like to define... an interface,  a base class that implements part of the interface, and child classes that implement the rest of the interface.<br>
  Is there a way I can do this? I tried this in C# but the compiler complains that the base class does not fully implement the interface.
  If possible I would like a solution that would work for C# and PHP</p>
  
  <p><img src="https://i.stack.imgur.com/Fyr4g.gif" alt="enter image description here"></p>