Function serves_token 

pub fn serves_token(token: &str) -> bool

Is token an <intent-id>#<criterion-id> reference: two lowercase slugs joined by one #? The same pattern the issue schema declares for serves.

use majordomus_cli::intent_plan::serves_token;
assert!(serves_token("intent-lifecycle#stage-is-derived"));
assert!(!serves_token("intent-lifecycle"));
assert!(!serves_token("Intent#x"));
assert!(!serves_token("a#b#c"));