What is the burden of demonstrating error on appeal of a search and seizure of a cigarette butt?

³ Tousant also challenges the search and seizure of additional items from his car, including a rental agreement, cigarette butt, and an interim driver's license, but he fails to advance any arguments specifically addressing those items in his opening brief. He thus fails to meet his burden on appeal demonstrating error. (See People v. Sullivan (2007) 151 Cal.App.4th 524, 549, 59 Cal.Rptr.3d 876 [" "We must indulge in every presumption to uphold a judgment, and it is defendant's burden on appeal to affirmatively demonstrate errorit will not be presumed" "].)