What is the need of an interface in this code? C#

Question

Can purely using inheritance solve this problem. I don't see the need to use an interface
https://www.sololearn.com/compiler-playground/c8wu17946fEq

Answer 1

In that simple example, and from a purely functional point of view, no, there's probably not much point. It would be more interesting to do so if Draw had functionality that Brush and Spray would benefit from, and if it made sense to consider a Brush and a Spray as instances of "Draw", which does sound sensible, in the context of a meaningful class hierarchy (although I think the names here are a bit weird, I wouldn't call a class a verb).