title: Extend interface to an abstract class
body: <p>I have an interface (move) that should move some shapes.</p>
  
  <pre><code>interface Move { move(); }
  abstract class Shape : Move
  
  class Circle : Shape
  class Square : Shape
  class Triangle : Shape
  </code></pre>
  
  <p>My doubt is, I must have an interface which moves Shapes but only Circle and Triangle should be able to be moved, so how do I "remove" the interface from Square? Should I remove the interface from Shape and add it manually on Circle and Triangle? I'm kinda confused with this. Hope someone can help me out.</p>