anchor.diff:                      list_unification_1(Es1, Es2);
                   false ->
                       SubTrees1 = subtrees(Exp1),
  -                     SubTrees2 = subtrees(Exp2),
  +                    SubTrees2 = subtrees(Exp2),
                       case length(SubTrees1) == length(SubTrees2) of
                           true ->
                               unification(SubTrees1, SubTrees2);
  
positive.code:             [DefLoc|| {_Name, _SrcLoc, DefLoc} <- VarLocs]
      end.
  
  is_meta_list(Node) ->
      is_meta_list_variable(Node) orelse is_meta_clause_list(Node) orelse
          is_meta_function_arity_list(Node).
  
negative.code: list_unification_1(Exp1, Exp2)->
      LEs1 = [E||E<-Exp1,is_list(E)],
      LEs2 = [E||E<-Exp2,is_list(E)],
      case LEs1==[] andalso LEs2==[] of
          false ->
              case  has_meta_list(Exp1) of
                  false ->
                      list_unification_2(Exp1, Exp2);
                  true ->
                      list_unification_3(Exp1,Exp2)
              end;
          true ->
              list_unification_3(Exp1, Exp2)
      end.
  