val wc_c : t -> string -> int
(** count characters in a file *)
+val head : t -> string -> string array
+(** return first 10 lines of a file *)
+
+val head_n : t -> int -> string -> string array
+(** return first N lines of a file *)
+
+val tail : t -> string -> string array
+(** return last 10 lines of a file *)
+
+val tail_n : t -> int -> string -> string array
+(** return last N lines of a file *)
+