anchor.diff:  check_gexpr(['progn'|B], Env, L, St) -> check_gbody(B, Env, L, St);
   check_gexpr(['if'|B], Env, L, St) -> check_gif(B, Env, L, St);
   check_gexpr([call,[quote,erlang],[quote,Fun]|As], Env, L, St) ->
  -    check_gexpr([Fun|As], Env, L, St);      %Pass the buck
  -check_gexpr([call|_], _, L, St) ->          %Other calls not allowed
  +    check_gexpr([Fun|As], Env, L, St);          %Pass the buck
  +check_gexpr([call|_], _, L, St) ->              %Other calls not allowed
       illegal_guard_error(L, St);
   %% Finally the general case.
   check_gexpr([Fun|As], Env, L, St0) when is_atom(Fun) ->
  
positive.code: 
  form(F) ->
      module([{['define-module',dummy],1},
          {F,2}]).
  
  %% module(Forms) -> {ok,[Warning]} | {error,[Error],[Warning]}.
  %% module(Forms, Options) -> {ok,[Warning]} | {error,[Error],[Warning]}.
  
negative.code: 
  check_gargs(Args, Env, L, St) ->
      case is_proper_list(Args) of
          true -> check_gexprs(Args, Env, L, St);
          false -> add_error(L, bad_gargs, St)
      end.
  
  check_gexprs(Es, Env, L, St) ->
  