Is there an instruction stating that one of the facts to be determined, and as to which the jury must be convinced beyond a reasonable doubt, was whether defendant committed the crime?

"Here, an instruction stating that one of the facts to be determined, and as to which the jury must be convinced beyond a reasonable doubt, was whether defendant committed the crime, could have been requested and, if requested, should have been given. (People v. Sears, supra, 2 Cal.3d 180 (84 Cal.Rptr. 711, 465 P.2d 847).) Such an instruction could have pointed out that the evidence on that score was conflicting between the eyewitnesses to the crime on one side, and the witnesses as to the defendant's presence elsewhere on the other side, and that in evaluating their testimony the jury should be guided by the rules declared elsewhere in the instructions.