2.2c KVL

Kirchhoff's Voltage Law

Kirchhoff’s voltage law (KCL) states that net voltage flowing out of (or into) any closed loop must equal zero.

\usepackage[straightvoltages]{circuitikz}
\begin{document}
\begin{circuitikz}
\draw
(-2.2,0) to[generic, v^=$v_1$] (0,0)
to [generic, v^=$v_2$] (2.2,0)
(0,-2.2) to[generic, v=$v_3$] (0,0);
\end{circuitikz}
\end{document}

In other words,
$$v_1-v_2+v_3=0,$$
where $v_2$ is flowing out of the node and is therefore subracted.