Can Embedded Python Blocks have callbacks?

I'm trying to use a callback to set a variable in an embedded python block.  Using the tutorial (https://wiki.gnuradio.org/index.php/Embedded_Python_Block) as an example I added the function below.  I've found that this callback never gets called when I update this value from a GUI.  Should it be?

    def set_example_param(self, example_param):          print("here")