\begin{circus}
\circchannel c
\end{circus}
\begin{circus}
\circprocess Pin \circdef \circbegin
	\circspot c	\then \Skip \\
\circend \\
\circprocess Pout \circdef \circbegin
	\circspot c \then \Skip \\
\circend \\
\circprocess Pins \circdef
	Pin \interleave
	(Pin
	)
\\
\circprocess P \circdef Pins \lpar \lchanset c \rchanset \rpar Pout \\
\end{circus}