Generate a configuration object that specifies a univariate Poisson mixture kernel, where users can
specify the hyperparameters of the conjugate Gamma prior, i.e. the kernel is a \(Poisson(\tau) \)
and \(\tau\sim Gamma(\alpha_0,\beta_0)\).
In AntMAN we assume the following
parametrization of the Gamma density:
$$p(x\mid a,b )= \frac{b^a x^{a-1}}{\Gamma(a)} \exp\{ -bx \}, \quad x>0.$$