instance method example for clarification

chapters/classes_and_objects/class-methods-and-instance-methods.md

@@ -9,6 +9,7 @@ You want to create a class methods and instance methods.
 
 ## Solution
 
+### Class Method
 {% highlight coffeescript %}
 class Songs
   @_titles: 0    # Although it's directly accessible, the leading _ defines it by convention as private property.
@@ -30,6 +31,25 @@ song.get_count()
 # => TypeError: Object #<Songs> has no method 'get_count'
 {% endhighlight %}
 
+### Instance Method
+class Songs
+  _titles: 0    # Although it's directly accessible, the leading _ defines it by convention as private property.
+
+  get_count: ->
+    @_titles
+
+  constructor: (@artist, @title) ->
+    @_titles++
+
+song = new Songs("Rick Astley", "Never Gonna Give You Up")
+song.get_count()
+# => 1
+
+Songs.get_count()
+# => TypeError: Object function Songs(artist, title) ... has no method 'get_count'
+{% endhighlight %}
+
+
 ## Discussion
 
 Coffeescript will store class methods (also called static methods) on the object itself rather than on the object prototype (and thus on individual object instances), which conserves memory and gives a central location to store class-level values.