code: func (h *Handle) XfrmStateFlush(proto Proto) error {
  	req := h.newNetlinkRequest(nl.XFRM_MSG_FLUSHSA, unix.NLM_F_ACK)
  
  	req.AddData(&nl.XfrmUsersaFlush{Proto: uint8(proto)})
  
  	_, err := req.Execute(unix.NETLINK_XFRM, 0)
  	return err
  }
docs: // XfrmStateFlush will flush the xfrm state on the system.
  // proto = 0 means any transformation protocols
  // Equivalent to: `ip xfrm state flush [ proto XFRM-PROTO ]`