`dict.get` always returns `None` if the key is not defined, so you don't have to specify it explicitly. Also, since the key defined in the `Parametizer` class, `params['embed']` is guaranteed to work: https://github.com/cbmi/serrano/blob/27fec3471e84feb79f080d698a2fb89b5cc3f471/serrano/resources/concept.py#L72-L82