Remove Linked List Elements

class Solution:    # @param {ListNode} head    # @param {integer} val    # @return {ListNode}    def removeElements(self, head, val):        dummy = ListNode(0)        dummy.next = head        pre, cur = dummy, head        while cur:            if cur.val == val:                pre.next = cur.next            else:                pre = cur            cur = cur.next        return dummy.next