pub fn parse(s: &str) -> Result<String>
k3F9xQ2mLp, https://semora/d/k3F9xQ2mLp/page.md, wss://semora/ws/d/k3F9xQ2mLp → k3F9xQ2mLp.
k3F9xQ2mLp
https://semora/d/k3F9xQ2mLp/page.md
wss://semora/ws/d/k3F9xQ2mLp