[improvement] organize type definitions

packages/utils/deep-clone.ts

@@ -4,8 +4,10 @@ export function deepClone(obj: object): object {
   if (Array.isArray(obj)) {
     return obj.map(item => deepClone(item));
   }
+
   if (typeof obj === 'object') {
     return deepAssign({}, obj);
   }
+
   return obj;
 }