Feat: add new Markdown parser (#39800)

and change all the challenges to new `md` format.

curriculum/challenges/english/10-coding-interview-prep/data-structures/invert-a-binary-tree.md

@@ -5,58 +5,92 @@ challengeType: 1
 forumTopicId: 301704
 ---
 
-## Description
-<section id='description'>
-Here will we create a function to invert a binary tree. Given a binary tree, we want to produce a new tree that is equivalently the mirror image of this tree. Running an inorder traversal on an inverted tree will explore the nodes in reverse order when compared to the inorder traversal of the original tree. Write a method to do this called <code>invert</code> on our binary tree. Calling this method should invert the current tree structure. Ideally, we would like to do this in-place in linear time. That is, we only visit each node once and we modify the existing tree structure as we go, without using any additional memory. Good luck!
-</section>
+# --description--
 
-## Instructions
-<section id='instructions'>
+Here will we create a function to invert a binary tree. Given a binary tree, we want to produce a new tree that is equivalently the mirror image of this tree. Running an inorder traversal on an inverted tree will explore the nodes in reverse order when compared to the inorder traversal of the original tree. Write a method to do this called `invert` on our binary tree. Calling this method should invert the current tree structure. Ideally, we would like to do this in-place in linear time. That is, we only visit each node once and we modify the existing tree structure as we go, without using any additional memory. Good luck!
 
-</section>
+# --hints--
 
-## Tests
-<section id='tests'>
-
-```yml
-tests:
-  - text: The <code>BinarySearchTree</code> data structure should exist.
-    testString: assert((function() { var test = false; if (typeof BinarySearchTree !== 'undefined') { test = new BinarySearchTree() }; return (typeof test == 'object')})());
-  - text: The binary search tree should have a method called <code>invert</code>.
-    testString: assert((function() { var test = false; if (typeof BinarySearchTree !== 'undefined') { test = new BinarySearchTree() } else { return false; }; return (typeof test.invert == 'function')})());
-  - text: The <code>invert</code> method should correctly invert the tree structure.
-    testString: assert((function() { var test = false; if (typeof BinarySearchTree !== 'undefined') { test = new BinarySearchTree() } else { return false; }; if (typeof test.invert !== 'function') { return false; }; test.add(4); test.add(1); test.add(7); test.add(87); test.add(34); test.add(45); test.add(73); test.add(8); test.invert(); return test.inorder().join('') == '877345348741'; })());
-  - text: Inverting an empty tree should return <code>null</code>.
-    testString: assert((function() { var test = false; if (typeof BinarySearchTree !== 'undefined') { test = new BinarySearchTree() } else { return false; }; if (typeof test.invert !== 'function') { return false; }; return (test.invert() == null); })());
-
-```
-
-</section>
-
-## Challenge Seed
-<section id='challengeSeed'>
-<div id='js-seed'>
+The `BinarySearchTree` data structure should exist.
 
 ```js
-var displayTree = (tree) => console.log(JSON.stringify(tree, null, 2));
-function Node(value) {
-  this.value = value;
-  this.left = null;
-  this.right = null;
-}
-function BinarySearchTree() {
-  this.root = null;
-  // Only change code below this line
-  
-  // Only change code above this line
-}
+assert(
+  (function () {
+    var test = false;
+    if (typeof BinarySearchTree !== 'undefined') {
+      test = new BinarySearchTree();
+    }
+    return typeof test == 'object';
+  })()
+);
 ```
 
-</div>
+The binary search tree should have a method called `invert`.
 
+```js
+assert(
+  (function () {
+    var test = false;
+    if (typeof BinarySearchTree !== 'undefined') {
+      test = new BinarySearchTree();
+    } else {
+      return false;
+    }
+    return typeof test.invert == 'function';
+  })()
+);
+```
 
-### After Test
-<div id='js-teardown'>
+The `invert` method should correctly invert the tree structure.
+
+```js
+assert(
+  (function () {
+    var test = false;
+    if (typeof BinarySearchTree !== 'undefined') {
+      test = new BinarySearchTree();
+    } else {
+      return false;
+    }
+    if (typeof test.invert !== 'function') {
+      return false;
+    }
+    test.add(4);
+    test.add(1);
+    test.add(7);
+    test.add(87);
+    test.add(34);
+    test.add(45);
+    test.add(73);
+    test.add(8);
+    test.invert();
+    return test.inorder().join('') == '877345348741';
+  })()
+);
+```
+
+Inverting an empty tree should return `null`.
+
+```js
+assert(
+  (function () {
+    var test = false;
+    if (typeof BinarySearchTree !== 'undefined') {
+      test = new BinarySearchTree();
+    } else {
+      return false;
+    }
+    if (typeof test.invert !== 'function') {
+      return false;
+    }
+    return test.invert() == null;
+  })()
+);
+```
+
+# --seed--
+
+## --after-user-code--
 
 ```js
 BinarySearchTree.prototype = Object.assign(
@@ -113,11 +147,24 @@ BinarySearchTree.prototype = Object.assign(
 );
 ```
 
-</div>
-</section>
+## --seed-contents--
 
-## Solution
-<section id='solution'>
+```js
+var displayTree = (tree) => console.log(JSON.stringify(tree, null, 2));
+function Node(value) {
+  this.value = value;
+  this.left = null;
+  this.right = null;
+}
+function BinarySearchTree() {
+  this.root = null;
+  // Only change code below this line
+  
+  // Only change code above this line
+}
+```
+
+# --solutions--
 
 ```js
 var displayTree = (tree) => console.log(JSON.stringify(tree, null, 2));
@@ -141,7 +188,4 @@ function BinarySearchTree() {
   }
     // Only change code above this line
 }
-
 ```
-
-</section>