def all_slots_for(self, cls: ClassDefinition) -> List[SlotDefinitionName]:
if not cls.is_a:<EOL><INDENT>return cls.slots<EOL><DEDENT>else:<EOL><INDENT>return [sn for sn in self.all_slots_for(self.schema.classes[cls.is_a]) if sn not in cls.slot_usage]+ cls.slots<EOL><DEDENT>
Return all slots for class cls