code: def addClass(self, className):
          '''
              addClass - append a class name to the end of the "class" attribute, if not present
  
                  @param className <str> - The name of the class to add
          '''
          className = stripWordsOnly(className)
  
          if not className:
              return None
  
          if ' ' in className:
              # Multiple class names passed, do one at a time
              for oneClassName in className.split(' '):
                  self.addClass(oneClassName)
              return
  
          myClassNames = self._classNames
  
          # Do not allow duplicates
          if className in myClassNames:
              return
  
          # Regenerate "classNames" and "class" attr.
          #   TODO: Maybe those should be properties?
          myClassNames.append(className)
  
          return Nonf addClass(self, className):
          '''
              addClass - append a class name to the end of the "class" attribute, if not present
  
                  @param className <str> - The name of the class to add
          '''
          className = stripWordsOnly(className)
  
          if not className:
              return None
  
          if ' ' in className:
              # Multiple class names passed, do one at a time
              for oneClassName in className.split(' '):
                  self.addClass(oneClassName)
              return
  
          myClassNames = self._classNames
  
          # Do not allow duplicates
          if className in myClassNames:
              return
  
          # Regenerate "classNames" and "class" attr.
          #   TODO: Maybe those should be properties?
          myClassNames.append(className)
  
          return None
docs: addClass - append a class name to the end of the "class" attribute, if not present
  
                  @param className <str> - The name of the class to add