# bar --- add revision bars to an unformatted document

   if [file -ne [arg 1]]
      error [arg 1]": not found"
   fi
   if [file -ne [arg 2]]
      error [arg 2]": not found"
   fi
   term -nobreak
   [arg 1]> find "%@[cc]mc" -x |D _
   [arg 2]> find "%@[cc]mc" -x |D _
      :D diff -r >[arg 2]
   term -break
