LinkedList 5-141. Circular linked list

class Solution:
    def hasCycle(self, head: ListNode) -> bool:
        seen = set()
        while head:
            if head in seen:
                return True
            seen.add(head)
            head = head.next
        return False

class Solution:
    def hasCycle(self,head:ListNode) ->bool:
        seen=set()
        while head:
            if head in seen:
                return True
            seen.add(head)
            head = head.next
        return False