code: def add(self, item, value):
          
          if item in self.__dict__[self.ATTRIBUTES].keys():
              raise AttributeError('%s already exists' % item)
          setattr(self, item, value)
docs: Add an attribute value to our object instance.
  
          :param str item: Application attribute name
          :param any value: Value to associate with the attribute
          :raises: AttributeError