diff --git a/buggy.py b/buggy.py
--- a/buggy.py
+++ b/buggy.py
@@ -8,13 +8,13 @@
 
 
 class Solution:
-    def maximumGap(self, nums: list) -> int:
+    def maximumGap(self, nums: List[int]) -> int:
         nums = sorted(nums)
         min = float("-inf")
         if len(nums) < 2:
             return 0
         for i in range(len(nums) - 1):
-            x = abs(nums[i] - undefined_variable)
+            x = abs(nums[i] - nums[i + 1])
             if min < x:
                 min = x
         return min
