anchor.diff:  
   [source,javascript]
   ----
  -export let sayHello = function() {
  +export var sayHello = function() {
       console.log("Hello, world!");
   };
  -export let sayThings = function(xs) {
  +export var sayThings = function(xs) {
       for(let x of xs) {
           console.log(x);
       }
   };
  -export let reactHello = function() {
  +export var reactHello = function() {
       return <div>Hello world!</div>
   };
   ----
  
positive.code: 
  [source,javascript]
  ----
  export let sayHello = function() {
      console.log("Hello, world!");
  };
  ----
  
negative.code: 
  [source,javascript]
  ----
  export var sayHello = function() {
      console.log("Hello, world!");
  };
  export var sayThings = function(xs) {
      for(let x of xs) {
          console.log(x);
      }
  