Albert

I've removed this issue from the milestone. We will handle it after #181

@gvdr it's somewhat possible, but multiplying this matrix with a multivariate random variable isn't possible as there's no multiplication defined for `Matrix{RandomVariable}` and `RandomVariable` types in the toolbox. It's not...

Okay, so we don't throw an error just yet. The merge of the new GraphPPL is coming. The error perhaps should be thrown on the inference step.

@wouterwln this can be closed?