'Call callback and goto in sequence.
Args:
callback (callable or str): Callback to run before goto. If
the callback returns a string, this is used to replace
the `goto` string before going to the next node.
goto (str): The target node to go to next (unless replaced
by `callable`)..
raw_string (str): The original user input.'

def callback_goto(self, callback, goto, raw_string):

    if callback:
        goto = (self.callback(callback, raw_string) or goto)
    if goto:
        self.goto(goto, raw_string)
