def __getitem__(self, alias):
        try:
            return self._connections.connections[alias]
        except __HOLE__:
            self._connections.connections = {}
        except KeyError:
            pass

        try:
            backend = get_backend(alias)
        except KeyError:
            raise KeyError('%s is not a valid backend alias' % alias)

        connection = get_connection(backend)
        connection.open()
        self._connections.connections[alias] = connection
        return connection
dataset/ETHPy150Open ui/django-post_office/post_office/connections.py/ConnectionHandler.__getitem__