What is the test for section 654 of the California Criminal Code when it comes to sentencing for sexual assault?

"The purpose of section 654 is to prevent multiple punishment for a single act or omission, even though that act or omission violates more than one statute and thus constitutes more than one crime. Although the distinct crimes may be charged in separate counts and may result in multiple verdicts of guilt, the trial court may impose sentence for only one offensethe one carrying the highest punishment. [Citation.]" (People v. Liu (1996) 46 Cal.App.4th 1119, 1135, fn. omitted.)