code: def count_slow(self, page_size=10, vtimeout=10):
          
          n = 0
          l = self.get_messages(page_size, vtimeout)
          while l:
              for m in l:
                  n += 1
              l = self.get_messages(page_size, vtimeout)
          return n
docs: Deprecated.  This is the old 'count' method that actually counts
          the messages by reading them all.  This gives an accurate count but
          is very slow for queues with non-trivial number of messasges.
          Instead, use get_attribute('ApproximateNumberOfMessages') to take
          advantage of the new SQS capability.  This is retained only for
          the unit tests.