persistent.py 文件源码

def viewkeys(self):
            """Set-like object providing a view of index keys.

            >>> index = Index('/tmp/diskcache/index')
            >>> index.clear()
            >>> index.update({'a': 1, 'b': 2, 'c': 3})
            >>> keys_view = index.viewkeys()
            >>> 'b' in keys_view
            True

            :return: keys view

            """
            return KeysView(self)