Let $\gamma$ be a 1-cycle (linear combination of closed curves). Then $\gamma$ is called a boundary of an open set $G\subseteq \mathbb{C}$ if $n_{\gamma }(a)=$ 1;;$1$ for each $a\in G$ and $n_{\gamma }(a)=$ 1;;$0$ for $a\in \mathbb{C}-(G\bigcup im(\gamma ))$.