docs: public static Object fromRDF(Object input, JsonLdOptions options, RDFParser parser)
              throws JsonLdError {
  
          final RDFDataset dataset = parser.parse(input);
  
          // convert from RDF
          final Object rval = new JsonLdApi(options).fromRDF(dataset);
  
          // re-process using the generated context if outputForm is set
          if (options.outputForm != null) {
              if (JsonLdConsts.EXPANDED.equals(options.outputForm)) {
                  return rval;
              } else if (JsonLdConsts.COMPACTED.equals(options.outputForm)) {
                  return compact(rval, dataset.getContext(), options);
              } else if (JsonLdConsts.FLATTENED.equals(options.outputForm)) {
                  return flatten(rval, dataset.getContext(), options);
              } else {
                  throw new JsonLdError(JsonLdError.Error.UNKNOWN_ERROR,
                          "Output form was unknown: " + options.outputForm);
              }
          }
          return rval;
      }