Visiting localhost:8000/hello/John/58, for example, will trigger the hello route resulting in the string Hello, 58 year old named John! being sent to the browser. If an <age> string was passed in that can't be parsed as a u8, the route won't get called, resulting in a 404 error. The official community support channels are the #rocket IRC channel on the Mozilla IRC Server at irc.mozilla.org and the bridged Rocket room on Matrix. If you're not familiar with IRC, we recommend chatting through Matrix via Riot or via the Kiwi web IRC client. You can learn more about IRC via Mozilla's Getting Started with IRC guide.