global s
procedure main()
   &trace := -1
   s := "abcdef"
   &subject := "123456"
   &pos := 4
   every tracer(1)
   every foo(&pos | &subject | &pos[1] | &subject[2:5])
end

procedure tracer(a)
   local i
   static j
   i := 2
   j := 3
   suspend a | i | j | s | &subject |
      &pos | &random | &trace | &subject[3:4] | &pos[1] |
      s[3] | s[3:5] | &random[1] | &trace[1] | &subject[2:5][1]
end

procedure foo(s)
   return s
end