Update mandel-17.py

Author: mandel-17

two-sum/mandel-17.py

@@ -6,4 +6,5 @@ def twoSum(self, nums: List[int], target: int) -> List[int]:
             second_value = target - v
 
             if second_value in nums[i+1:]:
-                return [i, nums[i+1:].index(second_value) + i+1]
+                return [i, nums[i+1:].index(second_value) + i+1]
+