1 files changed, 5 insertions, 1 deletions
diff --git a/engine/stack.go b/engine/stack.go
index 8bcff6f..dd10dd6 100644
--- a/engine/stack.go
+++ b/engine/stack.go
@@ -1,6 +1,6 @@
 package engine
 
-type Stack []*Card
+type Stack []IsCard
 
 func (s Stack) Contains(predicate func(c IsCard) bool) bool {
 	for _, c := range s {
@@ -30,3 +30,7 @@ func (s Stack) Pop() IsCard {
 		return c
 	}
 }
+
+func (s Stack) Hidden() Stack {
+	return Secrets(len(s))
+}