def add_message(self, keys, messages):
        d_to_use = self

        for key in keys:
            d_to_use = d_to_use['children'][key]

        if not isinstance(messages, list):
            messages = [messages]

        d_to_use['messages'].extend(messages)
:param keys: ordered list of project ids from parent to node (e.g. ['parent._id', 'node._id'])
dataset/ETHPy150Open CenterForOpenScience/osf.io/website/notifications/utils.py/NotificationsDict.add_message