Format snippets

snippets/groupBy.md

@@ -10,10 +10,12 @@ Groups the elements of an array based on the given function.
 
 ```js
 const groupBy = (arr, fn) =>
-  arr.map(typeof fn === 'function' ? fn : val => val[fn]).reduce((acc, val, i) => {
-    acc[val] = (acc[val] || []).concat(arr[i]);
-    return acc;
-  }, {});
+  arr
+    .map(typeof fn === 'function' ? fn : val => val[fn])
+    .reduce((acc, val, i) => {
+      acc[val] = (acc[val] || []).concat(arr[i]);
+      return acc;
+    }, {});
 ```
 
 ```js