code: def get_alt(self, option):
          
          assert hasattr(self, option)
  
          alt = option + '_alt'
          if not hasattr(self, alt):
              return ''
          return ', '.join(self.__dict__[alt])
docs: Return the alternative values of an option
  
          Parameters
          ----------
          option: str
              option name
  
          Returns
          -------
          str
              a string of alternative options