3.7.3.1 SoCallback

void SoCallbackCB( void *data, SoAction *action)

A Python implementation must look like:

def mySoCallbackCallback(myCallbackData, myAction):
    '''Callback for ..

    myCallbackData can be any type or class
    myAction is an iv.SoAction
    '''

    # your Python code

    # no use to return something