procedure main() # remove lines
   removelines("foo.bar",3,2) | stop("Failed to remove lines.")
end

procedure removelines(fn,start,skip)

   f := open(fn,"r") | fail                  # open to read
   every put(F := [],|read(f))               # file to list
   close(f)

   if *F < start-1+skip then fail
   every F[start - 1 + (1 to skip)] := &null # mark delete

   f := open(fn,"w") | fail                  # open to rewrite
   every write(\!F)                          # write non-nulls
   close(f)
   return                                    # done
end