@Override
    public Response push(Context context, Shape shape, Receiver next) {
        if (!context.receivedShapes(shape, selector)) {
            return next.apply(context, shape);
        } else {
            return Response.CONTINUE;
        }
    }
Filters out shapes that yield shapes when applied to a selector.
smithy-model/src/main/java/software/amazon/smithy/model/selector/NotSelector.java