

def add_callback(self, callback, section=None, key=None):
    "Add a callback to be called when a specific section or key has\n        changed. If you don't specify a section or key, it will call the\n        callback for all section/key changes.\n\n        Callbacks will receive 3 arguments: the section, key and value.\n\n        .. versionadded:: 1.4.1\n        "
    if ((section is None) and (key is not None)):
        raise Exception('You cannot specify a key without a section')
    self._callbacks.append((callback, section, key))

dataset/ETHPy150Open kivy/kivy/kivy/config.py ConfigParser.add_callback/original