code: def translate_args(self, mu, k_agg, return_p=False):
          
          if return_p:
              return nbinom_ztrunc_p(mu, k_agg), k_agg
          else:
              return mu, k_agg
docs: %(super)s
  
          The keyword argument return_p computes the p values used to define the
          the truncated negative binomial