Q$9)(10\%)$

Consider the following cascade connection of systems$-$

$z_1=-x_1+2x_2+u_1$

$x_2=-x_2+u_2$

$z=-z^3+z_1^2{x}_1-2x_2+z_1{x}_2$

$($i$)$ Is it locally input$-$to$-$state$-$rable?

$($ii$)$ Is it input$-$to$-$state$-$stable?