anchor.diff:  
   check_gargs(Args, Env, L, St) ->
       check_foreach(fun (A, S) -> check_gexpr(A, Env, L, S) end,
  -		  fun (S) -> add_error(L, bad_gargs, S) end,
  -		  St, Args).
  +                  fun (S) -> add_error(L, bad_gargs, S) end,
  +                  St, Args).
   
   check_gexprs(Es, Env, L, St) ->
       foldl(fun (E, S) -> check_gexpr(E, Env, L, S) end, St, Es).
  
positive.code: bad_meta_error(L, A, St) ->
      add_error(L, {bad_meta,A}, St).
  
  multi_var_error(L, V, St) ->
      add_error(L, {multi_var,V}, St).
  
  
negative.code:     lfe_io:format1("multiple variable: ~w", [S]);
  format_error({redef_fun,F}) ->
      lfe_io:format1("redefining function: ~w", [F]);
  format_error({bad_fdef,F}) ->
      lfe_io:format1("bad function definition: ~w", [F]);
  format_error(illegal_literal) -> "illegal literal";
  format_error(illegal_pattern) -> "illegal pattern";
  format_error(illegal_guard) -> "illegal guard";
  