is Program.Plugins -> stage1WithPlugins(program)

        is Program.Stage1Sequence -> stage1WithPlugins(program)

        is Program.Script -> reduceScriptProgram(program)

        is Program.Staged -> reduceStagedProgram(program)

        else -> throw IllegalArgumentException("Unsupported `$program'")
    }

    private
    fun reduceEmptyProgram(): Static =

        when (programTarget) {