'Insert an item at specified position index.
>>> d=Dict( ((6, \'six\'), (9, \'neuf\'), (4, \'quatre\')) )
>>> d.insert(1, \'40\', \'quarante\')
>>> d
{6: \'six\', \'40\': \'quarante\', 9: \'neuf\', 4: \'quatre\'}'

def insert(self, index, key, value):

    if (key in self):
        raise UniqKeyError((_("Insert    error:    key    '%s'    ready    exists") % key))
    _index = index
    if (index < 0):
        index += len(self._value_list)
    if (not (0 <= index <= len(self._value_list))):
        raise IndexError((_("Insert    error:    index    '%s'    is    invalid") % _index))
    for (item_key, item_index) in self._index.iteritems():
        if (item_index >= index):
            self._index[item_key] += 1
    self._index[key] = index
    self._key_list.insert(index, key)
    self._value_list.insert(index, value)
