Cannot use specific parameter title for custom model config

[AndrewZhang599]

Describe the bug
Instantiating custom model with parameters that have "_" are unable to be used

To Reproduce

import pandas as pd
import arviz as az
import numpy as np
import pandas as pd
import pytensor
import matplotlib.pyplot as plt 
import hssm
import ssms.basic_simulators

shrink_spot_model = hssm.HSSM(data=test_dataset_sim, 
                              model="custom_model",
                              model_config = {
                                  "list_params": ["v", "a", "z", "t", "p_outer", "p_inner", "p_target", "r", "sda", "alpha"],
                                  "bounds": { 
                                      "v": (-3.0, 3.0), 
                                      "a": (0.3, 3.0), 
                                      "z": (0.1, 0.9),
                                      "t": (0.001, 2),
                                      "p_outer": (-1, 1), 
                                      "p_inner": (-1, 1), 
                                      "p_target": (-1, 1), 
                                      "r": (0.001, 3), 
                                      "sda": (0.001, 3), 
                                      "alpha": (0.001, 5)
                                    
                                  }, 
                                  "backend": "jax"  

                              },
                              loglik= onnx_path,
                              loglik_kind="approx_differentiable", 
                              p_outlier = 0, 

Screenshots

Additional context
Works so long as "_" is not a part of parameter name.

[AlexanderFengler]

I will have a closer look at what can be done on the _get_prefix method, but I am inclined to instead check and throw exception if models have parameters with underscores in them. What do you think @digicosmos86?

[digicosmos86]

I think this is kind of limiting - there should be plenty of use cases where underscores can be helpful. Let's see if there is another way that gets us around this issue

[AlexanderFengler]

Let's add more documentation on this but disallow _ in parameter names.
Paul conceded :)