docs: public void writeClosePortal(String portal) {
      ensureBuffer();
      int pos = out.writerIndex();
      out.writeByte(CLOSE);
      out.writeInt(0);
      out.writeByte('P'); // 'S' to close a prepared statement or 'P' to close a portal
      Util.writeCStringUTF8(out, portal);
      out.setInt(pos + 1, out.writerIndex() - pos - 1);
    }