Update the output following a change of the input selection

def callback_c(*args, **kwargs):
    'Update the output following a change of the input selection'
    #da = kwargs['dash_app']

    session_state = kwargs['session_state']

    calls_so_far = session_state.get('calls_so_far', 0)
    session_state['calls_so_far'] = calls_so_far + 1

    user_counts = session_state.get('user_counts', None)
    user_name = str(kwargs['user'])
    if user_counts is None:
        user_counts = {user_name:1}
        session_state['user_counts'] = user_counts
    else:
        user_counts[user_name] = user_counts.get(user_name, 0) + 1

    return "Args are [%s] and kwargs are %s" %(",".join(args), str(kwargs))