         
         return lhs.age > rhs.age
     }
+    
+    // allow to "override the operator"
+    static func ==(lhs: Son, rhs: Son) -> Bool {
+        
+        return lhs.age == rhs.age
+    }
 }
 
 let larry2 = Son(name: "Larry", age: 2, truck: "Blue Dump")

    
    print("larry 10 >= larry 7")
}
/*:
 Above we created a `Son` class inheriting from `Father` and also conforming to the `Comparable` protocol. The `Son` class need to implement all the functions defined in the `Comparable` protocol. Next we create four instances of a `Son` class exercising the comparison operators of `<, <=, >=, >`.
 */

    }
}

let runnerWalker: Runnable = RunnerWalker(walker: Walker(direction: "North"))

runnerWalker.run(speed: 4.5)
/*:
