def deleteDuplicates(self, head):
        cur = head
        while cur:
            runner = cur.next
            while runner and runner.val == cur.val:
                runner = runner.next
            cur.next = runner
            cur = runner
        return head
Test that trying to stop following a non-existent user fails.
dataset/ETHPy150Open kamyu104/LeetCode/Python/remove-duplicates-from-sorted-list.py/Solution.deleteDuplicates--crossover with--dataset/ETHPy150Open pytent/pytentd/tentd/tests/blueprints/test_followers.py/test_delete_missing_follower