docs: public void writeDescribe(Describe describe) {
      ensureBuffer();
      int pos = out.writerIndex();
      out.writeByte(DESCRIBE);
      out.writeInt(0);
      if (describe.statement != 0) {
        out.writeByte('S');
        out.writeLong(describe.statement);
      } else if (describe.portal != null) {
        out.writeByte('P');
        Util.writeCStringUTF8(out, describe.portal);
      } else {
        out.writeByte('S');
        Util.writeCStringUTF8(out, "");
      }
      out.setInt(pos + 1, out.writerIndex() - pos- 1);
    }