anchor.diff:  atom_option(Key) -> Key.
   
   is_filename(T) ->
  -    try filename:flatten(T) of
  -        Filename -> Filename
  +    try filename:flatten(T)
       catch error: _ -> no
       end.    
   
  
positive.code:     %% C1  C2
      %%        C3  C4
      [Cr1|disjoint_crs([Cr2|Crs])];
  disjoint_crs([{C1,C2},{C3,C4}|Crs]) when C1 == C3 ->
      %% C1     C2
      %% C3       C4
      [{C1,C2}|disjoint_crs(add_element({C2+1,C4}, Crs))];
  
negative.code:     %% io:fwrite("move1: ~p\n", [{Sts,Cr}]),
      [ St || N <- Sts,
              {Crs,St} <- (element(N, NFA))#nfa_state.edges,
              Crs =/= epsilon,             % Not an epsilon transition
              in_crs(Cr, Crs) ].
  
  in_crs({C1,C2}, [{C3,C4}|_Crs]) when C1 >= C3, C2 =< C4 -> true;
  