code: def expected_value(self):
          '''
          Compute expected value.
  
          Returns:
              Expected value.
          '''
          alpha = self.__success + self.__default_alpha
          beta = self.__failure + self.__default_beta
  
          try:
              expected_value = alpha / (alpha + beta)
          except ZeroDivisionError:
              expected_value = 0.0
          return expected_valuf expected_value(self):
          '''
          Compute expected value.
  
          Returns:
              Expected value.
          '''
          alpha = self.__success + self.__default_alpha
          beta = self.__failure + self.__default_beta
  
          try:
              expected_value = alpha / (alpha + beta)
          except ZeroDivisionError:
              expected_value = 0.0
          return expected_value
docs: Compute expected value.
  
          Returns:
              Expected value.