diff --git a/data/part-10/3-oo-programming-techniques.md b/data/part-10/3-oo-programming-techniques.md
index 1c09debee..b5a095d4a 100644
--- a/data/part-10/3-oo-programming-techniques.md
+++ b/data/part-10/3-oo-programming-techniques.md
@@ -59,11 +59,11 @@ class Product:
     def price(self):
         return self.__price
 
-    def cheaper(self, Product):
-        if self.__price < Product.price:
+    def cheaper(self, other: Product) -> Product:
+        if self.__price < other.price:
             return self
         else:
-            return Product
+            return other
 ```
 
 ```python