anchor.diff:  
   -export([test_msg/0,
            send_test/4,
  -         test/0
  +         test/0,
  +         double_dot/1
   ]).
   
   %%====================================================================
  
positive.code: 	is_mixed([#mime_part{encoding={_, "text/html", _}}|T]) -> is_mixed(T);
  	is_mixed(_) -> true.
  	
  
  invent_mime_boundary() ->
      string:copies("=", 10) ++ list_rand(boundary_chars(), 30).
          
  
negative.code: %    "'()+_,-./=?"
      .
  
  %% Double dots at the start of a line, conform to Section 4.5.2 of RFC 2821
  double_dot([$.|T]) ->
      double_dot(T, [$., $.]);
  double_dot(L) ->
      double_dot(L, []).
  
      double_dot([], Acc) ->
          lists:reverse(Acc);
      double_dot([13, 10, $. | T], Acc) ->
          double_dot(T, [$., $., 10, 13|Acc]);
      double_dot([H|T], Acc) ->
          double_dot(T, [H|Acc]).
  
  
  join([H1, H2| T], S) when is_list(H1), is_list(H2), is_list(S) ->
      H1 ++ S ++ join([H2| T], S);
  %join([C1, C2 | Chars], S) when is_integer(C1), is_integer(C2), is_list(S) ->
  