'Delete item at position index. May raise IndexError.
>>> d=Dict( ((6, \'six\'), (9, \'neuf\'), (4, \'quatre\')) )
>>> del d[1]
>>> d
{6: \'six\', 4: \'quatre\'}'

def __delitem__(self, index):

    if (index < 0):
        index += len(self._value_list)
    if (not (0 <= index < len(self._value_list))):
        raise IndexError((_('list    assignment    index    out    of    range    (%s/%s)') % (index, len(self._value_list))))
    del self._value_list[index]
    del self._key_list[index]
    for (key, item_index) in self._index.iteritems():
        if (item_index == index):
            del self._index[key]
            break
    for (key, item_index) in self._index.iteritems():
        if (index < item_index):
            self._index[key] -= 1
