remove last block occurrences

fixed.

lib/register/instructions/branch.rb

@@ -45,6 +45,11 @@ module Register
       self.next.assemble_all(io, labels) if self.next
     end
 
+    def each_label labels =[] , &block
+      super
+      self.label.each_label(labels , &block) if self.label
+    end
+
   end
 
   class IsZero < Branch

lib/register/instructions/label.rb

@@ -56,5 +56,12 @@ module Register
       self.position = position
       self.next.set_position(position,labels)
     end
+
+    def each_label labels =[] , &block
+      return if labels.include?(self)
+      labels << self
+      block.yield(self)
+      super
+    end
   end
 end