请编写程序实现单链表插入、删除结点等基本算法。给定一个单链表和一系列插入、删除结点的操作序列，输出实施上述操作后的链表。单链表数据域值为整数。请编写程序实现单链表插入、删除结点等基本算法。

在Python中，我们可以首先定义一个简单的单链表节点类`ListNode`，然后实现插入和删除结点的功能。这里是一个基础版本的实现：

class ListNode:
    def __init__(self, val=0, next=None):
        self.val = val
        self.next = next

# 插入结点函数
def insert_node(head, val):
    new_node = ListNode(val)
    if not head:
        head = new_node
    else:
        current = head
        while current.next:
            current = current.next
        current.next = new_node
    return head

# 删除结点函数（基于值删除）
def delete_node(head, val):
    if not head:
        return head
    elif head.val == val:
        return head.next
    else:
        current = head
        while current.next and current.next.val != val:
            current = current.next
        if current.next:
            current.next = current.next.next
        return head

# 测试示例
# 初始化一个空链表
head = None
# 操作序列（例如：[5, 3, 7]表示插入5，然后插入3，再插入7）
operations = [5, 3, 7]
for op in operations:
    if op == "insert":
        head = insert_node(head, int(operations[operations.index(op) + 1]))
    else:  # 假设删除操作是"delete"
        head = delete_node(head, int(operations[operations.index(op) + 1]))

# 输出当前链表的节点值
current = head
while current:
    print(current.val, end=" -> ")
    current = current.next
print("None")  # 结尾的None表示链表结束