code: def _remove_empty_pars(pars, pars_oi, dims_oi):
      
      pars = list(pars)
      for par, dim in zip(pars_oi, dims_oi):
          if par in pars and np.prod(dim) == 0:
              del pars[pars.index(par)]
      return pars
docs: Remove parameters that are actually empty. For example, the parameter
      y would be removed with the following model code:
  
          transformed data { int n; n <- 0; }
          parameters { real y[n]; }
  
      Parameters
      ----------
      pars: iterable of str
      pars_oi: list of str
      dims_oi: list of list of int
  
      Returns
      -------
      pars_trimmed: list of str