val in_index : t -> input -> (data -> bool) -> bool
val retrieve_generalizations : t -> input -> dataset
val retrieve_unifiables : t -> input -> dataset
+ (* the int is the number of symbools that matched, the list
+ * is sorted with biggest matches first. the same data may match
+ * twice, and thus appear twice with different number of matches *)
val retrieve_generalizations_sorted : t -> input -> (data * int) list
val retrieve_unifiables_sorted : t -> input -> (data * int) list
end