val cache_examine: cache -> cache_key -> cache_elem
val cache_add_failure: cache -> cache_key -> int -> cache
val cache_add_success: cache -> cache_key -> Cic.term -> cache
val cache_examine: cache -> cache_key -> cache_elem
val cache_add_failure: cache -> cache_key -> int -> cache
val cache_add_success: cache -> cache_key -> Cic.term -> cache