@deepstan and I respectfully request any assistance in implementing a custom prior distribution in STAN.
I have attached a one-page description of the model for the rat tumor example, along with relevant R scripts. We were successful in implementing the beta-binomial model but having some issues to make it work for our DS(G,m) prior model ( https://www.nature.com/articles/s41598-018-28130-5), which is an extension of the vanilla beta prior.
Thank you for your time and consideration. Please let us know if we can provide any additional information or insights into our request.