1 files changed, 1 insertions, 0 deletions
diff --git a/tree.sig b/tree.sig
index e06ca68..8967f83 100644
--- a/tree.sig
+++ b/tree.sig
@@ -14,4 +14,5 @@ signature TREE = sig
         ('v option -> 'a * 'v option) -> 'a * ('k, 'v) t
 
   val print: ('k, 'v) t -> ('k -> string) -> ('v -> string) -> unit
+  val size: ('k, 'v) t -> int
 end