Marked some internal classes as @Private so Yardoc does not flag them…

… as 'undocumented'

lib/hamster/list.rb

@@ -1353,6 +1353,7 @@ def done?
       @list.empty?
     end
 
+    # @private
     class Left < Realizable
       def initialize(splitter, buffer, mutex)
         super()
@@ -1380,6 +1381,7 @@ def realize
       end
     end
 
+    # @private
     class Right < Realizable
       def initialize(splitter, mutex)
         super()

lib/hamster/sorted_set.rb

@@ -1283,6 +1283,7 @@ def direction(item)
         @comparator.call(item, @item)
       end
 
+      # @private
       class Empty
         def initialize(comparator); @comparator = comparator; end
         def natural_order?; false; end
@@ -1364,6 +1365,7 @@ def direction(item)
         item <=> @item
       end
 
+      # @private
       class Empty < AVLNode::Empty
         def initialize;           end
         def natural_order?; true; end