##
4.1 Dynamic placeholder - no cache

The template:

      Dynamic variable:  $voom

The command line and the output:

      % voom='Voom!' python x.py --env
      Dynamic variable:  Voom!

The generated code:

      write('Dynamic variable:  ')
      write(filter(VFS(SL,"voom",1))) # generated from '$voom' at line 1, col 20.
      write('\n')

Just what we expected, like any other dynamic placeholder.