What is the test for a defendant to establish murder by lying in wait?

² The rejected portion of defendant's requested instruction stated, "To establish murder by lying-in-wait the prosecution must prove the elements of concealment of purpose together with 'a substantial period of watching and waiting for an opportune time to act, and ... immediately thereafter, a surprise attack on an unsuspecting victim from a position of advantage' " (relying on and citing People v. Ruiz (1988) 44 Cal.3d 589, 615, 244 Cal.Rptr. 200, 749 P.2d 854, and People v. Mattison (1971) 4 Cal.3d 177, 183, 93 Cal.Rptr. 185, 481 P.2d 193).