\begin{circuslaw}{distr-prefix-par-3}
\begin{circusaction*}
  c \then \Skip \circseq (\Skip \lpar ns_1 | cs | ns_2 \rpar A) ~ \equiv ~ \Skip \lpar ns_1 | cs | ns_2 \rpar (c \then A)
  \also
  \provided ~ c \notin cs
\end{circusaction*}
\end{circuslaw}
