src/Pure/General/output_primitives.ML

--- a/src/Pure/General/output_primitives.ML	Sat Mar 18 12:24:56 2017 +0100
+++ b/src/Pure/General/output_primitives.ML	Sat Mar 18 12:46:52 2017 +0100
@@ -9,6 +9,7 @@
   type output = string
   type serial = int
   type properties = (string * string) list
+  val ignore_outputs: output list -> unit
   val writeln_fn: output list -> unit
   val state_fn: output list -> unit
   val information_fn: output list -> unit