change the index name(s).

        * call with one argument:
            1. list of new index names (to replace all old names)

        * call with two arguments:
            1. old index name(s) (or index/indices)
            2. new index name(s)

def rename_index(self, *args):
        '''change the index name(s).

        * call with one argument:
            1. list of new index names (to replace all old names)

        * call with two arguments:
            1. old index name(s) (or index/indices)
            2. new index name(s)
        '''
        if len(args) == 1:
            new_indices = args[0]
            old_indices =force_list(self.indices.keys())
        else:
            old_indices, new_indices = args
            old_indices, single = convert_index_to_keys(self.indices, old_indices)
            if single:
                old_indices, new_indices = [old_indices], [new_indices]

        if len(new_indices) != len(old_indices):
            raise ValueError('Length of update indices (%s) does not match '
                             'existing indices (%s)' %
                             (len(new_indices), len(old_indices)))

        map(MI_check_index_name, new_indices)

        if len(new_indices) != len(set(new_indices)):
            raise ValueError('New indices names are not unique: %s' % (new_indices,))

        od_replace_key(self.indices, old_indices, new_indices, multi=True)