@Override
  public String toString() {
    IndentedLineBuffer out = new IndentedLineBuffer();

    SerializationContext sCxt = SSE.sCxt((SSE.defaultPrefixMapWrite));

    boolean first = true;
    for (Triple t : triples) {
      if (!first) out.print("\n");
      else first = false;
      // Adds (triple ...)
      // SSE.write(buff.getIndentedWriter(), t) ;
      out.print("(");
      WriterNode.outputPlain(out, t, sCxt);
      out.print(")");
    }
    out.flush();
    return out.toString();
  }