code: public Document readDocument(InputStream is, ProvFormat format, String baseuri) {
          return readDocument(is, format, pFactory, baseuri);
      }
docs: Reads a Document from an input stream, using the parser specified by the format argument.
  @param is an input stream
  @param format one of the input formats supported by ProvToolbox
  @param baseuri a base uri for the input stream document
  @return a Document