anchor.diff:  
   %% @doc Return true if the given character is a non-character code point
   %% as defined by https://tools.ietf.org/html/rfc3454#appendix-C.4
  +-spec is_non_character_code_points(char()) -> boolean().
   is_non_character_code_points(C) ->
       (16#FDD0 =< C andalso C =< 16#FDEF)
           orelse (16#FFFE =< C andalso C =< 16#FFFF)
  
positive.code: 
  %% @doc Return true if the given character is a tagging character as defined by
  %% https://tools.ietf.org/html/rfc3454#appendix-C.9
  is_tagging_char(C) ->
      C == 16#E0001 orelse
          (16#E0020 =< C andalso C =< 16#E007F).
  
negative.code: %%% coding: utf-8
  %%% @doc
  %%% This is a helper module that will validate a utf-8
  %%% string based on sasl_prep profile as defined in
  %%% https://tools.ietf.org/html/rfc4013
  %%% @end
  
  -module(epgsql_sasl_prep_profile).
  
  -export([ validate/1
          ]).
  
  -spec validate(iolist()) -> iolist().
  validate(Str) ->
      lists:foreach(fun(F) ->
                        lists:any(F, unicode:characters_to_list(Str, utf8))
  