def queryMetadata(self, datasetType, format=None, dataId={}, **rest):

        """Returns the valid values for one or more keys when given a partial

        input collection data id.

        Parameters

        ----------

        datasetType - str

            The type of dataset to inquire about.

        key - str

            A key giving the level of granularity of the inquiry.

        format - str, tuple

            An optional key or tuple of keys to be returned.

        dataId - DataId, dict

            The partial data id.

        **rest -

            Keyword arguments for the partial data id.

        Returns

        -------

        A list of valid values or tuples of valid values as specified by the format (defaulting to the same as

        the key) at the key's level of granularity.

        """

...

        if format is None:

            format = (key,)

        else:

            format = sequencify(format)

...