anchor.diff:  
   read_line_1(Io, P, C0, L0) ->
       case io:get_line(Io, P) of
  -        {error,Error} -> {error,Error};
  +        {error,Error} -> {error,{L0,io,Error}};
           Cs0 ->
               case scan_sexpr(C0, Cs0, L0) of
                   {done,{ok,Ret,_L1},_Cs1} -> {ok,Ret};
  
positive.code: read(Io, Prompt) ->
      case io:request(Io, {get_until,unicode,Prompt,?MODULE,scan_sexpr,[1]}) of
          {ok,Sexpr,_} -> {ok,Sexpr};
          {error,Error,_} -> {error,Error};
          {eof,_} -> eof
      end.
  
negative.code: %% Copyright (c) 2008-2016 Robert Virding
  %%
  %% Licensed under the Apache License, Version 2.0 (the "License");
  %% you may not use this file except in compliance with the License.
  