anchor.diff:           ,lookup_by_channel/1
           ]).
   
  --export([url/1
  -         ,parse_url/1
  -         ,valid_url/1
  +-export([parse_url/1
            ,valid_uri/1
            ,has_valid_uri/1
           ]).
  
positive.code:         {error, _} = Err ->
              Err
      end.
  
  valid_url(Url) ->
      valid_uri(parse_url(Url)).
  
  -spec valid_uri(uri:parsed_uri() | {error, term()}) ->
                         {valid, type(), uri:parsed_uri()} |
  
negative.code:         [] -> Token
      end.
  
  parse_url(Url) ->
      case uri:parse(Url) of
          {ok, Uri} ->
  