anchor.diff:  get_bitspecs(Ss) ->
       case lfe_bits:get_bitspecs(Ss) of
           {ok,Sz,Ty} -> {Sz,Ty};
  -        {error,Error} -> erlang:error(Error)
  +        {error,Error} -> eval_error(Error)
       end.
   
   is_posint_list([I|Is]) when is_integer(I), I >= 0 ->
  
positive.code: eval_lit_map([K,V|As], Env) ->
      [{eval_lit(K, Env),eval_lit(V, Env)}|eval_lit_map(As, Env)];
  eval_lit_map([], _) -> [].
  
negative.code: match_symb(S, Val, Pbs, _) ->
      %% Check if Symb already bound.
      case find(S, Pbs) of
          {ok,_} -> eval_error({multi_var,S});  %Already bound, multiple var
          error -> {yes,store(S, Val, Pbs)}       %Not yet bound
      end.
  
  