Function token_subject 

pub fn token_subject<'a>(
    account: &'a str,
    kind: SubjectKind<'a>,
    handle: Option<&'a str>,
    pds_did: &'a str,
    pds_hostname: &'a str,
    client_id: &'a ClientId,
    scopes: &'a [&'a str],
    now: OffsetDateTime,
) -> Subject<'a>

Builds the Subject::Token a gate judges before a token is issued to client_id for account: an authorization code exchanged, or a refresh token rotated. scopes are the wire strings the token would carry.