update snippets 47-62

snippets/flattenDepth.md

@@ -11,5 +11,8 @@ Omit the second element, `depth` to flatten only to a depth of `1` (single flatt
 const flattenDepth = (arr, depth = 1) =>
   depth != 1 ? arr.reduce((a, v) => a.concat(Array.isArray(v) ? flattenDepth(v, depth - 1) : v), [])
   : arr.reduce((a, v) => a.concat(v), []);
-// flattenDepth([1,[2],[[[3],4],5]], 2) -> [1,2,[3],4,5]
+```
+
+```js
+flatten([1,[2],3,4]) -> [1,2,3,4]
 ```