code: public Reader asReader() {
          Reader r = getReader();
          if (r != null) return r;
          String s = getString();
          if (s != null) return new StringReader(s);
          InputStream is = fromStreamOrBufferOrUrl();
          if (is != null) return readerFrom(is);
          throw resourceUnaccessible();
      }
docs: Returns the resource as a reader, converting it if necessary.
  <p>
  See the docs of {@linkplain RResult} for notes on data conversion.
  @return reader