<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def properties_changed(self, properties, changed_properties, invalidated_properties):
 value = changed_properties.get('Value') """ Called when a Characteristic property has changed. """

        if value is not None:
            self.service.device.characteristic_value_updated(characteristic=self, value=bytes(value))