anchor.diff:                  [
                       {"text/plain", get_piqi_piq},
                       {"application/json", get_piqi_json},
  -                    {"application/protobuf", get_piqi_pb}
  +                    {"application/x-protobuf", get_piqi_pb}
                   ];
               'POST' ->
                   [
                       {"application/json", unused_value},
  -                    {"application/protobuf", unused_value},
  +                    {"application/x-protobuf", unused_value},
                       {"text/plain", unused_value}
                   ]
           end,
  
positive.code: % Utility functions
  %
  
  format_to_content_type('pb') -> "application/protobuf";
  format_to_content_type('json') -> "application/json";
  format_to_content_type('piq') -> "text/plain".
  
  
  content_type_to_format("application/protobuf") -> 'pb';
  content_type_to_format("application/json") -> 'json';
  content_type_to_format("text/plain") -> 'piq';
  content_type_to_format(_) -> 'undefined'.
  
negative.code:     IsKnownType =
          case wrq:get_req_header("content-type", ReqData) of
              "application/json" -> true;
              "application/x-protobuf" -> true;
              % allow content-type to be undefined when the body is empty
              'undefined' when IsEmptyBody -> true;
              _ -> false
  