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.