code: func (h *Handle) XfrmPolicyFlush() error {
  	req := h.newNetlinkRequest(nl.XFRM_MSG_FLUSHPOLICY, unix.NLM_F_ACK)
  	_, err := req.Execute(unix.NETLINK_XFRM, 0)
  	return err
  }
docs: // XfrmPolicyFlush will flush the policies on the system.
  // Equivalent to: `ip xfrm policy flush`