listF :: (Eq a) => [(a, F b c)] -> F (a, b) (a, c)
listF tagged_fudgets
listF operate in parallel, indepdenetly of one
another. The high level output streams from the individual
fudgets are tagged and merged into a single stream. The input stream,
which must be tagged, is split up and fed to the appropriate fudget.
(tag,msg) is sent to the fudget tagged tag.
(tag,msg) comes from the fudget tagged tag.
tagged_fudgets :: [(a, F b c)]
