Exercise 6.9 Opamp configuration with series impedance in the loop

In the circuit below, the opamp is almost ideal: $r_{\mathit{in}}\to \infty$, $r_{\mathit{out}}=0$), but this opamp does have a finite voltage gain $A$.

a)

Derive an expression for the output impedance $z_o$ of the circuit (looking into the port identified by $v_{\mathit{out}}$).

b)

Draw a bode plot (asymptotes only is sufficient) of this output impedance. Indicate the values of the poles/zeros (x-axis) and flat parts (y-axis).