More a style question. I have a lot of places where I use the on_change handle to trigger a callback. Often I do not even use information on what exactly changed.
Bokeh however requires the exact signature of three arguments. E.g. *args is not allowed:
ValueError: Callback functions must have signature func(attr, old, new), got func(*args)
an option here would be
def callback(attr, old, new):
but these are never used, to indicate that they are not used I could do
def callback(_, __, ___)
but this may perhaps not be better.
What would be in your opinion the cleanest way of dealing with the above?