code: def add(self, *items):
          
          for item in items:
              self.unsorted.append(item)
              key = item[0]
              self.index[key] = item
          return self
docs: Add items to be sorted.
          @param items: One or more items to be added.
          @type items: I{item}
          @return: self
          @rtype: L{DepList}