[Python] Why am I getting "hascycle" error for this question?

I am trying to solve a leetcode problem where we have to find if a cycle exists in a LinkedList.

This is the code that I tried but I am getting an error which says I have a cycle in the list. What am I doing wrong?

class Solution:
def hasCycle(self, head: Optional[ListNode]) -> bool:

slow,fast=head
while fast and fast.next:
fast=fast.next.next

if slow is fast:
return True
return False


This is the error I am getting:

TypeError: cannot unpack non-iterable ListNode object
^^^^^^^^^
slow,fast=head
Line 10 in hasCycle (Solution.py)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ret = Solution().hasCycle(param_1)
Line 40 in _driver (Solution.py)
_driver()
Line 53 in <module> (Solution.py)

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