code: func DeleteInterface(t *testing.T, ifName string) {
  	icmd.RunCommand("ip", "link", "delete", ifName).Assert(t, icmd.Success)
  	icmd.RunCommand("iptables", "-t", "nat", "--flush").Assert(t, icmd.Success)
  	icmd.RunCommand("iptables", "--flush").Assert(t, icmd.Success)
  }
docs: // DeleteInterface deletes a network interface