code: def init_return(self, ret_type):
          
          if self._ret_type == ret_type:
              return
          if ret_type == "straight":
              self._interp = self._lnlfn.interp
          if ret_type == "profile":
              self._profile_loglike_spline(self._lnlfn.interp.x)
              #self._profile_loglike(self._lnlfn.interp.x)
              self._interp = self._prof_interp
          elif ret_type == "marginal":
              self._marginal_loglike(self._lnlfn.interp.x)
              self._interp = self._marg_interp
          elif ret_type == "posterior":
              self._posterior(self._lnlfn.interp.x)
              self._interp = self._post_interp
          else:
              raise ValueError("Did not recognize return type %s" % ret_type)
  
          self._ret_type = ret_type
docs: Specify the return type.
  
          Note that this will also construct the 
          '~fermipy.castro.Interpolator' object
          for the requested return type.