add In_buf.skip

src/core/in_buf.ml

@@ -255,3 +255,12 @@ let of_seq ?(bytes = Bytes.create _default_buf_size) seq : t =
        bs.len <- loop 0
    end
     :> t)
+
+let skip (self : #t) (n : int) : unit =
+  let n = ref n in
+  while !n > 0 do
+    let slice = fill_buf self in
+    let len = min !n slice.len in
+    Slice.consume slice len;
+    n := !n - len
+  done

src/core/in_buf.mli

@@ -113,6 +113,9 @@ val input_all : ?buf:bytes -> #t -> string
 val copy_into : #t -> #Out.t -> unit
 (** Copy the entire stream into the given output. *)
 
+val skip : #t -> int -> unit
+(** [skip ic n] reads and dicards the next [n] bytes in [ic]. *)
+
 val input_line : ?buffer:Buffer.t -> #t -> string option
 (** Read a line from the input. Return [None] if the stream is empty.
    @param buffer a buffer to use to hold the line. *)