update snippets 78 - 96

snippets/promisify.md

@@ -14,6 +14,9 @@ const promisify = func =>
       func(...args, (err, result) =>
         err ? reject(err) : resolve(result))
     );
-// const delay = promisify((d, cb) => setTimeout(cb, d))
-// delay(2000).then(() => console.log('Hi!')) -> Promise resolves after 2s
+```
+
+```js
+const delay = promisify((d, cb) => setTimeout(cb, d))
+delay(2000).then(() => console.log('Hi!')) -> // Promise resolves after 2s
 ```