What is the effect of section 669 of the Criminal Code Code requiring a sentence be imposed on an offense for which defendant was originally granted probation so that there is the possibility of serving the sentence concurrently?

sentence be imposed on offense for which defendant originally granted probation so that there is the possibility of serving sentences concurrently].) We recognize that, as the parties agreed in their appellate briefing, sentence on one of the counts in fact should have been stayed under section 654. (People v. Allen, supra, 21 Cal.4th at pp. 866-867.) We focus on section 669, which has no applicability here in light of the requirement to stay one of the sentences, only to illustrate why the sentence the trial court purported to impose was unauthorized.