anchor.diff:      to_jiffy(Identifier, Metadata);
   format_element({link, Id1, Id2, Metadata}) ->
       to_jiffy(Id1, Id2, Metadata).
  +
  +uri_encode(B) when is_binary(B) ->
  +    list_to_binary(http_uri:encode(binary_to_list(B)));
  +uri_encode(S) ->
  +    http_uri:encode(S).
  
positive.code: 
  to_jiffy(Identifier, Metadata) ->
      {[
          {<<"identifier">>, Identifier},
          {<<"metdata">>, json_metadata(Metadata)}
      ]}.
  
  
negative.code: 
  to_resource(Identifier) ->
      % return resource URI for identifier
      iolist_to_binary([<<"/identifier/">>, uri_encode(Identifier)]).
  
  to_term({KeyValues}) ->
      [{Key, term_metadata(Value)} || {Key, Value} <- KeyValues].
  