code: def opacity(self, value):
          
  
          if value is not None:
              assert type(value) in (int, float), "'{0}' attribute: '{1}' type is not 'int' or 'float'!".format("opacity",
                                                                                                                value)
          if value > 1:
              value = 1
          elif value < 0:
              value = 0
  
          self.__opacity = float(value)
          self.__set_style_sheet()
docs: Setter for **self.__opacity** attribute.
  
          :param value: Attribute value.
          :type value: float