code: def get_elapsed(self, restart=True):
          '''
          Calculate time span.
          '''
          end = time.time()
          span = end - self.__start
          if restart:
              self.__start = end
          return spaf get_elapsed(self, restart=True):
          '''
          Calculate time span.
          '''
          end = time.time()
          span = end - self.__start
          if restart:
              self.__start = end
          return span
docs: Calculate time span.