Thanks for your help.  Tim's suggestions are nice, but I'd prefer to be
able to make the print/no-print decision on the fly, on a per-statement
basis.  On these grounds, Caleb's suggestion meets my needs best.  I
had actually tried using a semicolon, but of course irb then just waits
for the next statement.  Putting a 0 (or anything else) is a bit of a
kludge compared to the Python interpreter's convention, but it gets the
job done.

Thanks,

Michael