def get_tier_ids_for_linguistic_type(self, ling_type, parent=None):
        """Give a list of all tiers matching a linguistic type.

        :param str ling_type: Name of the linguistic type.
        :param str parent: Only match tiers from this parent, when ``None``
                           this option will be ignored.
        :returns: List of tiernames.
        :raises KeyError: If a tier or linguistic type is non existent.
        """
        return [t for t in self.tiers if
                self.tiers[t][2]['LINGUISTIC_TYPE_REF'] == ling_type and
                (parent is None or self.tiers[t][2]['PARENT_REF'] == parent)]
Give a list of all tiers matching a linguistic type.

        :param str ling_type: Name of the linguistic type.
        :param str parent: Only match tiers from this parent, when ``None``
                           this option will be ignored.
        :returns: List of tiernames.
        :raises KeyError: If a tier or linguistic type is non existent.