code: def remove(self, item):
          'Remove first occurence of item.  Raise ValueError if not found'
          i = self.index(item)
          del self._keys[i]
          del self._items[if remove(self, item):
          'Remove first occurence of item.  Raise ValueError if not found'
          i = self.index(item)
          del self._keys[i]
          del self._items[i]
docs: Remove first occurence of item.  Raise ValueError if not found