def get_tier_ids_for_linguistic_type(self, ling_type, parent=None):
return [t for t in self.tiers if<EOL>self.tiers[t][<NUM_LIT:2>]['<STR_LIT>'] == ling_type and<EOL>(parent is None or self.tiers[t][<NUM_LIT:2>]['<STR_LIT>'] == parent)]<EOL>
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.