code: def as_list(self, key):
          
          result = self[key]
          if isinstance(result, (tuple, list)):
              return list(result)
          return [result]
docs: A convenience method which fetches the specified value, guaranteeing
          that it is a list.
  
          >>> a = ConfigObj()
          >>> a['a'] = 1
          >>> a.as_list('a')
          [1]
          >>> a['a'] = (1,)
          >>> a.as_list('a')
          [1]
          >>> a['a'] = [1]
          >>> a.as_list('a')
          [1]