def add_on_change(key, callback):
    if _settings is None:
        add_on_change_callbacks[key].add(callback)
    else:
        _settings.add_on_change(key, callback)
Sets the callback to run when the given settings key changes.
dataset/ETHPy150Open Varriount/NimLime/nimlime_core/settings.py/add_on_change