pub async fn lookup(
context: &Context,
namespace: Namespace,
foreign_key: Option<&str>,
) -> Result<Option<String>>Expand description
Looks up most recently created token for a namespace / foreign key combination.
As there may be more than one such valid token, (eg. when a qr code token is withdrawn, recreated and revived later), use lookup() for qr-code creation only; do not use lookup() to check for token validity.
To check if a given token is valid, use exists().