<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def object_type(self):
 """ A read-only property that gives the object type as string; sensor, actuator, program, other. Used by WEB interface templates. """


        from .statusobject import AbstractSensor, AbstractActuator
        from .program import Program
        if isinstance(self, AbstractSensor):
            return 'sensor'
        elif isinstance(self, AbstractActuator):
            return 'actuator'
        elif isinstance(self, Program):
            return 'program'
        else:
            return 'other'