Update deepMapKeys

Resolves #1139

snippets/deepMapKeys.md

@@ -6,18 +6,19 @@ tags: object,recursion,advanced
 Deep maps an object's keys.
 
 Creates an object with the same values as the provided object and keys generated by running the provided function for each key.
-Use `Object.keys(obj)` to iterate over the object's keys. 
+Use `Object.keys(obj)` to iterate over the object's keys.
 Use `Array.prototype.reduce()` to create a new object with the same values and mapped keys using `fn`.
 
 ```js
-const deepMapKeys = (obj, f) =>
+const deepMapKeys = (obj, fn) =>
   Array.isArray(obj)
-    ? obj.map(val => deepMapKeys(val, f))
+    ? obj.map(val => deepMapKeys(val, fn))
     : typeof obj === 'object'
     ? Object.keys(obj).reduce((acc, current) => {
+        const key = fn(current);
         const val = obj[current];
-        acc[f(current)] =
-          val !== null && typeof val === 'object' ? deepMapKeys(val, f) : (acc[f(current)] = val);
+        acc[key] =
+          val !== null && typeof val === 'object' ? deepMapKeys(val, fn) : val;
         return acc;
       }, {})
     : obj;
@@ -51,4 +52,4 @@ const upperKeysObj = deepMapKeys(obj, key => key.toUpperCase());
   }
 }
 */
-```
+```