@classmethod
def set(cls, key, value):
    """ Insert or update parameter value for a key.

        .. note:: if the key already exists, the value will be updated

        :param str key: key to save
        :param value: value to save
        """
    multi = False
    if not isinstance(value, dict):
        value = {'value': value}
    else:
        multi = True
    if cls.is_exist(key):
        param = cls.from_primary_keys(key=key)
        param.update(value=value, multi=multi)
    else:
        cls.insert(key=key, value=value, multi=multi)
