How to use the notion.collection.NotionDate function in notion

)
            val = [[",".join(val)]]
        if prop["type"] in ["person"]:
            userlist = []
            if not isinstance(val, list):
                val = [val]
            for user in val:
                user_id = user if isinstance(user, str) else user.id
                userlist += [["‣", [["u", user_id]]], [","]]
            val = userlist[:-1]
        if prop["type"] in ["email", "phone_number", "url"]:
            val = [[val, [["a", val]]]]
        if prop["type"] in ["date"]:
            if isinstance(val, date) or isinstance(val, datetime):
                val = NotionDate(val)
            if isinstance(val, NotionDate):
                val = val.to_notion()
            else:
                val = []
        if prop["type"] in ["file"]:
            filelist = []
            if not isinstance(val, list):
                val = [val]
            for url in val:
                url = remove_signed_prefix_as_needed(url)
                filename = url.split("/")[-1]
                filelist += [[filename, [["a", url]]], [","]]
            val = filelist[:-1]
        if prop["type"] in ["checkbox"]:
            if not isinstance(val, bool):
                raise TypeError(
                    "Value passed to property '{}' must be a bool.".format(identifier)

)
                    )
            val = [[",".join(val)]]
        if prop["type"] in ["person"]:
            userlist = []
            if not isinstance(val, list):
                val = [val]
            for user in val:
                user_id = user if isinstance(user, str) else user.id
                userlist += [["‣", [["u", user_id]]], [","]]
            val = userlist[:-1]
        if prop["type"] in ["email", "phone_number", "url"]:
            val = [[val, [["a", val]]]]
        if prop["type"] in ["date"]:
            if isinstance(val, date) or isinstance(val, datetime):
                val = NotionDate(val)
            if isinstance(val, NotionDate):
                val = val.to_notion()
            else:
                val = []
        if prop["type"] in ["file"]:
            filelist = []
            if not isinstance(val, list):
                val = [val]
            for url in val:
                url = remove_signed_prefix_as_needed(url)
                filename = url.split("/")[-1]
                filelist += [[filename, [["a", url]]], [","]]
            val = filelist[:-1]
        if prop["type"] in ["checkbox"]:
            if not isinstance(val, bool):
                raise TypeError(