Calling JavaScript sibling function inside parent function

Question

I’m struggling with this and I haven’t found anything conclusive about this.

How can I call the function y() inside the function z() without altering the code's structure?

I tried using this but it didn’t work.

function x(){

    function y(){
    console.log("sal y")
  }
  
  function z(){
    console.log("sal z");
    y()
  }
 
}