Function session 

pub fn session<'a>(
    actor: &str,
    claims: impl IntoIterator<Item = (&'a str, &'a str)>,
    path: &str,
) -> Value

Session — who is asking, what the identity provider said about them, and where they are.

The claims are a Map[Str, Str] and not a record, because the set is the provider’s rather than the program’s: a tenant claim one deployment issues is one another has never heard of. They are copied in at the edge for the same reason the actor is — a fold that read them from a token would be a fold that could not replay (crate::render, §3.7).

path is the route, and it is built here for the same reason the other two are: a Mode B client renders the same view against a Session of its own, and a route the browser spelled differently than the server is a page that differs from the one it is hydrating.