'Give the subtypes triggered by the changes on the record according
to values that have been updated.
:param ids: list of a single ID, the ID of the record being modified
:type ids: singleton list
:param init_values: the original values of the record; only modified fields
are present in the dict
:type init_values: dict
:returns: a subtype xml_id or False if no subtype is trigerred'

@api.multi
def _track_subtype(self, init_values):

    return False
