Is a jury's failure to give a unanimity instruction harmless?

erroneous failure to give a unanimity instruction is harmless if disagreement among the jurors concerning the different specific acts proved is not reasonably possible."]; People v. Thompson (1995) 36 Cal.App.4th 843, 853 ["Where the record provides no rational basis, by way of argument or evidence, for the jury to distinguish between the various acts, and the jury must have believed beyond a reasonable doubt that defendant committed all acts if he committed any, the failure to give a unanimity instruction is harmless."].)