Draw the transition diagram of the finite-state automaton $\left(\mathcal{I}, \mathcal{S}, f, \mathcal{A}, \sigma_{0}\right)$.
$\mathcal{I}=\{a, b\}, \mathcal{S}=\left\{\sigma_{0}, \sigma_{1}, \sigma_{2}\right\}, \mathcal{A}=\left\{\sigma_{0}\right\}$