making pipes

How can I get the output of one process to be the input of another?

The process library says that the options pipes are pipe(-Stream), which
seems to mean I can not hand an already bound stream to process_create.

Is stream_pair/3 relevant?

Background: The goal is run dot and then use okular or display to open
the graph up so I can see it.  I've been looking at
http://cliopatria.swi-prolog.org/help/source/doc/home/vnc/prolog/src/ClioPatria/components/graphviz.pl?show=src for ideas, but it aims to embed in a web page and I'm having some difficulty following the full processing path.

I assume I will need to set the relevant pipes to binary mode.

Ross Boylan