Diagram(
  Terminal('$'),
  Optional(NonTerminal('blanks')),
  Choice(0,
    NonTerminal('module_directive'),
    NonTerminal('namespace_directive'),
    NonTerminal('include_directive'),
    NonTerminal('import_directive'),
    NonTerminal('using_directive'),
    NonTerminal('export_directive'),
    NonTerminal('language_directive'),
    NonTerminal('artefact_directive')),
  NonTerminal('end_of_line')
)