Feat: add new Markdown parser (#39800)

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

curriculum/challenges/english/10-coding-interview-prep/rosetta-code/accumulator-factory.md

@@ -1,58 +1,55 @@
 ---
-title: Accumulator factory
 id: 594810f028c0303b75339ace
+title: Accumulator factory
 challengeType: 5
 forumTopicId: 302222
 ---
 
-## Description
-<section id='description'>
-A problem posed by <a href='https://en.wikipedia.org/wiki/Paul_Graham_(programmer)' target='_blank'>Paul Graham</a> is that of creating a function that takes a single (numeric) argument and which returns another function that is an accumulator. The returned accumulator function in turn also takes a single numeric argument, and returns the sum of all the numeric values passed in so far to that accumulator (including the initial value passed when the accumulator was created).
-</section>
+# --description--
+
+A problem posed by [Paul Graham](https://en.wikipedia.org/wiki/Paul_Graham_(programmer)) is that of creating a function that takes a single (numeric) argument and which returns another function that is an accumulator. The returned accumulator function in turn also takes a single numeric argument, and returns the sum of all the numeric values passed in so far to that accumulator (including the initial value passed when the accumulator was created).
+
+# --instructions--
 
-## Instructions
-<section id='instructions'>
 Create a function that takes a number $n$ and generates accumulator functions that return the sum of every number ever passed to them.
-<strong>Rules:</strong>
+
+**Rules:**
+
 Do not use global variables.
-<strong>Hint:</strong>
+
+**Hint:**
+
 Closures save outer state.
-</section>
 
-## Tests
-<section id='tests'>
+# --hints--
 
-```yml
-tests:
-  - text: <code>accumulator</code> should be a function.
-    testString: assert(typeof accumulator === 'function');
-  - text: <code>accumulator(0)</code> should return a function.
-    testString: assert(typeof accumulator(0) === 'function');
-  - text: <code>accumulator(0)(2)</code> should return a number.
-    testString: assert(typeof accumulator(0)(2) === 'number');
-  - text: Passing in the values 3, -4, 1.5, and 5 should return 5.5.
-    testString: assert(testFn(5) === 5.5);
-
-```
-
-</section>
-
-## Challenge Seed
-<section id='challengeSeed'>
-
-<div id='js-seed'>
+`accumulator` should be a function.
 
 ```js
-function accumulator(sum) {
-
-}
+assert(typeof accumulator === 'function');
 ```
 
-</div>
+`accumulator(0)` should return a function.
 
+```js
+assert(typeof accumulator(0) === 'function');
+```
 
-### After Test
-<div id='js-teardown'>
+`accumulator(0)(2)` should return a number.
+
+```js
+assert(typeof accumulator(0)(2) === 'number');
+```
+
+Passing in the values 3, -4, 1.5, and 5 should return 5.5.
+
+```js
+assert(testFn(5) === 5.5);
+```
+
+# --seed--
+
+## --after-user-code--
 
 ```js
 const testFn = typeof accumulator(3) === 'function' && accumulator(3);
@@ -62,13 +59,15 @@ if (testFn) {
 }
 ```
 
-</div>
+## --seed-contents--
 
-</section>
+```js
+function accumulator(sum) {
 
-## Solution
-<section id='solution'>
+}
+```
 
+# --solutions--
 
 ```js
 function accumulator(sum) {
@@ -76,7 +75,4 @@ function accumulator(sum) {
     return sum += n;
   };
 }
-
 ```
-
-</section>