Retrieve values for a set of keys.

        Args:
            keys (str list): the list of keys whose value should be retrieved

        Keyword arguements:
            default (object): the value to use for non-existent keys
            coherent (bool): whether all fetched values should be "coherent",
                i.e no other update was performed on any of those values while
                fetching from the database.

        Yields:
            object: values for the keys, in the order they were passed

def mget(self, *keys, **kwargs):
        """Retrieve values for a set of keys.

        Args:
            keys (str list): the list of keys whose value should be retrieved

        Keyword arguements:
            default (object): the value to use for non-existent keys
            coherent (bool): whether all fetched values should be "coherent",
                i.e no other update was performed on any of those values while
                fetching from the database.

        Yields:
            object: values for the keys, in the order they were passed
        """
        default = kwargs.get('default')
        coherent = kwargs.get('coherent', False)
        for key in keys:
            yield self.get(key, default=default)