Nonlinear function for regression?

[zaizibai]

Hi HSSM developers,
thanks for making this wonderful package. In the previous HDDM package regression module, each parameter can only be modeled with a linear GLM function. There is also some regression software like brms in R which allow users to define a nonlinear function. For instance, in some cases, users may would like to assume drift rate change like a expoential function. Is there any possibility that HSSM supports this feature? Thanks a lot.