title: extension function in a kotlin using super
body: <p>How to call extension function of the base class in a derived class using the super keyword? </p>
  
  <p>I tried to call using super but it doesn't work.</p>
  
  <pre><code> open class abc {
       open fun aa() {
           println("function in abc")
       }
   }
   fun abc.sum() {
       println("extension function")
   }
   class ab: abc() {
  
       override fun aa() {
           super.aa()
           println("functon in ab")
       }
       fun sum() {
           super.sum()
           println("sum function")
       }
   }
   fun main(args: Array &lt; String &gt; ) {
       var aa: ab = ab()
       aa.aa()
       aa.aa()
       aa.sum()
   }
  </code></pre>
  
  <p>Here is the 16th number line error comes, I can't call the extension function.</p>