@abc.abstractproperty<EOL><INDENT>def d_distributionparams(self):<DEDENT>
pass<EOL>
Derivatives of `distributedparam` with respect to `distributionparams`.

        Returns:
            `d_distributionparams` (`dict` keyed by params in `distributionparams`)
                `d_distribution[param]` is a `numpy.ndarray` of `float` of
                shape `(ncats,)`, with `d_distributionparam[param][k]` giving
                the derivative of the `distributedparam` for category `k`
                with respect to `param` where `param` is in `distributionparams`.