Forgotten symbol in samples.json? about biscuit

[divarvel]

oh, good catch!

It is not a leftover from a previous version of the sample, rather to a small quirk in the encoding of checks' bodies in the biscuit-rust library. They are modeled as rules internally, and expiration is used as the predicate name for the rule head. But this rule head is not actually used, so it does not make sense to waste space on this name.

There is a little bootstrapping issue here, since the canonical way of defining checks in rust code is to use macros, but they are not available from the library itself (they are feature-gated). The check_expiration_date builds the check manually, but in a way that's a bit different from what's done in the macros / parser.

[divarvel]

see https://github.com/biscuit-auth/biscuit-rust/blob/main/biscuit-auth/src/token/builder.rs#L2278