Flowing <anything>
With the Flow, and then
finish} the <anything> call.
All of the "ing" calls (Flowing, Rolling, etc.) apply some action
to the preceding call, and then let that action replace the first part
of the "anything" call.
\begin{displaydance}
\phfour{b1n,g1s,g2n,b2s} & \phBB{g1s,b2n,b1s,g2n} & \phBB{b2n,g2n,g1s,b1s} & \pvfour{b1e,g2w,g1e,b2w} \cr
\cbox{before Recycle} & \cbox{before Flowing\\Contour the Line} & \cbox{after Flow} & finished \\
\end{displaydance