anchor.diff:          false ->
               invalid;
           true ->
  -            case lists:member(Classification, ClassificationsExplored0) andalso pruning() of  
  +            case classification_explored(Classification, ClassificationsExplored0) andalso pruning() of  
                   true ->
                       debug("Classification: ~p~n", [Classification]),
                       debug("Classifications explored: ~p~n", [ClassificationsExplored0]),
  
positive.code:         % DifferenceOmissionTypes = message_types(Omissions) -- message_types(BaseOmissions),
          % debug("DifferenceOmissionTypes: ~p~n", [DifferenceOmissionTypes]),
  
          case EarlyOmissions andalso EarlyCausality andalso not lists:member(EarlyClassification, GenClassificationsExplored0) of
              true ->
                  debug("~n", []),
                  % debug("Entering generation pass.~n", []),
  
negative.code:             false;
          _ ->
              true
      end.
  %% @private
  classification_explored(Classification, ClassificationsExplored) ->
      case Classification of 
          [] ->
              false;
          _ ->
              lists:member(Classification, ClassificationsExplored)
      end.
  