Makes slots linked list

slots used to ba an array of symbols
Now we have an object for each slot, that holds the name and the next_slot
relatively easy change, though quite broad

lib/slot_machine/slot.rb

@@ -18,11 +18,13 @@ module SlotMachine
 
     attr_reader :name , :next_slot
 
+    # initialize with just the name of the slot. Add more to the chain with set_next
     def initialize( name )
       raise "No name" unless name
-      @name =  name
+      @name = name
     end
 
+    #set the next_slot , but always at the end of the chain
     def set_next(slot)
       if(@next_slot)
         @next_slot.set_next(slot)
@@ -31,12 +33,18 @@ module SlotMachine
       end
     end
 
+    # return the length of chain, ie 1 plus however many more next_slots there are
+    def length
+      return 1 unless @next_slot
+      1 + @next_slot.length
+    end
+
+    # name of all the slots, with dot syntax
     def to_s
       names = name.to_s
       names += ".#{@next_slot}" if @next_slot
       names
     end
 
-
   end
 end