<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def add(self, *items):
 """ Add items to be sorted. @param items: One or more items to be added. @type items: I{item} @return: self @rtype: L{DepList} """

        for item in items:
            self.unsorted.append(item)
            key = item[0]
            self.index[key] = item
        return self