base.py

class DeclarativeMessage(Message):
    __metaclass__ = _DeclarativeMeta

    query = None
    query_rows = 1  # most common case
    role = None
    processor = None

    domain = None
    range = None
    rel_ = None
    rel_kwargs = None
    params = None
    features = None

    frequency = None
    time = None
    location = None
    mixins = None
    # approximate = None  # .approximate exists... should be .add_approximate

    def __init__(self, context, topic=None, **kwargs):
        self.relations = []
        self.topic = topic
        self.context = copy(context)  # so we can mutate w/out caring
        self.semantic_element = None

        if self.features is None:
            self.features = get_features_frame()
        else:
            # don't overwrite the original
            self.features = get_features_frame(self.features)

        if self.rel_kwargs is None:
            self.rel_kwargs = {}
        else:
            # don't overwrite the original
            self.rel_kwargs = deepcopy(self.rel_kwargs)