def on_sensor_change(obj=nil, &block)
	  @on_sensor_change_obj = obj
      @on_sensor_change = Proc.new { |device, obj_ptr, index, value|
	    yield self, @sensors[index], value, object_for(obj_ptr)
	}
      Klass.set_OnSensorChange_Handler(@handle, @on_sensor_change, pointer_for(obj))
    end
def on_sensor_change(obj=nil, &block)
	  @on_sensor_change_obj = obj
      @on_sensor_change = Proc.new { |device, obj_ptr, index, value|
	    yield self, @sensors[index], value, object_for(obj_ptr)
	}
      Klass.set_OnSensorChange_Handler(@handle, @on_sensor_change, pointer_for(obj))
    end
Sets a sensor change handler callback function. This is called when a sensor on the PhidgetInterfaceKit has changed by at least the sensitivity value that has been set for this input.

 @param [String] obj Object to pass to the callback function. This is optional.
 @param [Proc] Block When the callback is executed, the device and object are yielded to this block.
 @example
     ifkit.on_sensor_change do |device, input, value, obj|
       print "Analog Input  #{input.index}, changed to #{value}\n"
     end
 As this runs in it's own thread, be sure that all errors are properly handled or the thread will halt and not fire any more.
 @return [Boolean] returns true or raises an error