\begin{tikzpicture}
	\begin{pgfonlayer}{nodelayer}
		\node [style=none] (4) at (0, 4) {};
		\node [style=none] (5) at (1, 4) {};
		\node [style=none] (6) at (2, 4) {};
		\node [style=none] (7) at (5, 4) {};
		\node [style=none] (8) at (5, 0) {};
		\node [style=none] (9) at (0, 0) {};
		\node [style=none] (10) at (6, 4) {};
		\node [style=none] (11) at (7, 4) {};
		\node [style=none] (12) at (8, 4) {};
		\node [style=none] (13) at (11, 4) {};
		\node [style=none] (14) at (11, 0) {};
		\node [style=none] (15) at (6, 0) {};
	\end{pgfonlayer}
	\begin{pgfonlayer}{edgelayer}
		\draw (6.center) to (7.center);
		\draw (7.center) to (8.center);
		\draw (8.center) to (9.center);
		\draw (9.center) to (4.center);
		\draw (4.center) to (5.center);
		\draw (12.center) to (13.center);
		\draw (13.center) to (14.center);
		\draw (14.center) to (15.center);
		\draw (15.center) to (10.center);
		\draw (10.center) to (11.center);
	\end{pgfonlayer}
\end{tikzpicture}