code: def gen_source_models(self, gsim_lt):
          
          samples_by_lt_path = self.samples_by_lt_path()
          for i, rlz in enumerate(get_effective_rlzs(self)):
              smpath = rlz.lt_path
              num_samples = samples_by_lt_path[smpath]
              num_gsim_paths = (num_samples if self.num_samples
                                else gsim_lt.get_num_paths())
              yield LtSourceModel(
                  rlz.value, rlz.weight / num_samples, smpath, [],
                  num_gsim_paths, i, num_samples)
docs: Yield empty LtSourceModel instances (one per effective realization)