Provide a notion of fanout wherein a single input is passed to several consumers.
Share inputs with each of a list of processes in lockstep. Any values yielded by the processes are combined into a single yield from the composite process.
Share inputs with each of a list of processes in lockstep. If
none of the processes yields a value, the composite process will
mempty. The idea is to provide a handle on steps
only executed for their side effects. For instance, if you want to
run a collection of
ProcessTs that await but don't yield some
number of times, you can use 'fanOutSteps . map (fmap (const ()))'
followed by a