django 'set' object does not support indexing

在定义Model之后使用syncdb 同步的时候报出这个错误，检查之后发现是用错了。在model的Meta里面，排序这些用的应该是

ordering = ['last','first','middle']
unique_together = ['first','last','middle']
verbose_name_plural = "people"

如果是误写成

ordering = {'last','first','middle'}
        unique_together = {'first','last','middle'}
        verbose_name_plural = "people"

会出现 'set' object does not support indexing