$b = true
if $b {
	exec "exec0" {
		cmd => "sleep 10s",
		shell => "/bin/bash",
	}
}
exec "exec1" {
	cmd => "sleep 10s",
	shell => "/bin/bash",

	Depend => $b ?: Exec["exec0"],
	Before => Exec["exec2"],
}
exec "exec2" {
	cmd => "sleep 10s",
	shell => "/bin/bash",
}