base/ImmutableStack.rb in maroon-0.7.1 vs base/ImmutableStack.rb in maroon-0.8.0

@@ -11,10 +11,10 @@
   def push(element)
     ImmutableStack.new element, self
   end
 
   def self.empty
-    @@empty ||= self.new(nil, nil)
+    @empty ||= self.new(nil, nil)
   end
 
   def each
     yield head
     t = tail