Does appellant have to prove that he was an aider and abettor for his brother's commission of assault with a deadly weapon and battery with serious bodily injury against Hoyt?

and abettor for his brother's commission of the offenses of assault with a deadly weapon and battery with serious bodily injury against Hoyt.² Appellant further contends "acting in concert" is not synonymous with "aiding and abetting" (People v. Jones (1989) 212 Cal.App.3d 966, 969) because although acting in concert requires two or more people to act together, it does not require them to have the requisite intent for an aider and abettor, i.e., the "intent or purpose either of committing, or of encouraging or facilitating commission of, the offense." (People v. Chiu, supra, 59 Cal.4th 155, 161.) Thus according to appellant, the court's use of the term "in concert," indicates it found the battery and assault charges true without finding that he had the required intent to be an aider and abettor and, instead, found only that he acted in concert with his brother. We disagree.

"It is presumed that official duty is regularly performed." (Evid. Code, 664.) Further, an appellant has the affirmative duty to show error on appeal. (People v. Goodall (1951) 104 Cal.App.2d 242, 249.)