Browser History, leetcode solution

browser_history.py

class History:
    def __init__(self, url, prev=None, next_node=None):
        self.url = url
        self.prev = prev
        self.next = next_node

class BrowserHistory:
    def __init__(self, homepage: str):
        self.head = History(homepage)

    # time O(1)
    # space O(1)
    def visit(self, url: str) -> None:
        new_page = History(url)
        new_page.prev = self.head
        self.head.next = new_page
        self.head = self.head.next

    # time O(n)
    # space O(1)
    def back(self, steps: int) -> str:
        while steps and self.head.prev:
            self.head = self.head.prev
            steps -= 1

        return self.head.url

    # time O(n)
    # space O(1)
    def forward(self, steps: int) -> str:
        while steps and self.head.next:
            self.head = self.head.next
            steps -= 1

        return self.head.url