Python: Passing a class name as a parameter to a function?

class TestSpeedRetrieval(webapp.RequestHandler):
  """
  Test retrieval times of various important records in the BigTable database 
  """
  def get(self):
      commandValidated = True 
      beginTime = time()
      itemList = Subscriber.all().fetch(1000) 

      for item in itemList: 
          pass 
      endTime = time()
      self.response.out.write("<br/>Subscribers count=" + str(len(itemList)) + 
           " Duration=" + duration(beginTime,endTime)) 

How can I turn the above into a function where I pass the name of the class? In the above example, Subscriber (in the Subscriber.all().fetch statement) is a class name, which is how you define data tables in Google BigTable with Python.

I want to do something like this:

       TestRetrievalOfClass(Subscriber)  
or     TestRetrievalOfClass("Subscriber")  

Thanks, Neal Walters