Working admin.py

admin.py

class PostAdmin:
 ...
 ...
    // CommonMedia defined as a subclass of PostAdmin
    class CommonMedia:
      js = (
        'https://ajax.googleapis.com/ajax/libs/dojo/1.6.0/dojo/dojo.xd.js',
        '/appmedia/admin/js/editor.js',
      )
      css = {
        'all': ('/appmedia/admin/css/editor.css',),
      }

// Register new class
site.register(Post, PostAdmin)