/**
 * Write a function that concatenates two lists.
 */
var List = function() {
  'use strict';

  function concatenate(list1, list2) {

  }

  return {
    concatenate: concatenate
  };
};
@@ -130,16 +130,97 @@
 ist2) %7B%0A
+  %09%09list2.forEach(function(val) %7B%0A  %09%09%09list1.push(val);%0A  %09%09%7D);%0A  %09%09return list1;
 %0A  %7D%0A%0A  
@@ -264,8 +264,9 @@
 %0A  %7D;%0A%7D;
+%0A

Update concat-lists.js