code: def observe(self, success, failure):
          '''
          Observation data.
  
          Args:
              success:      The number of success.
              failure:      The number of failure.
  
          '''
          if isinstance(success, int) is False:
              if isinstance(success, float) is False:
                  raise TypeError()
          if isinstance(failure, int) is False:
              if isinstance(failure, float) is False:
                  raise TypeError()
  
          if success <= 0:
              raise ValueError()
          if failure <= 0:
              raise ValueError()
  
          self.__success += success
          self.__failure += failurf observe(self, success, failure):
          '''
          Observation data.
  
          Args:
              success:      The number of success.
              failure:      The number of failure.
  
          '''
          if isinstance(success, int) is False:
              if isinstance(success, float) is False:
                  raise TypeError()
          if isinstance(failure, int) is False:
              if isinstance(failure, float) is False:
                  raise TypeError()
  
          if success <= 0:
              raise ValueError()
          if failure <= 0:
              raise ValueError()
  
          self.__success += success
          self.__failure += failure
docs: Observation data.
  
          Args:
              success:      The number of success.
              failure:      The number of failure.