Under what circumstances will a defendant be found guilty of being a lookout for an armed robber?

Indeed, in affirming the special circumstances finding in 2007, this court implicitly recognized it was impossible to determine, from the jury's verdict and the evidence, whether defendant was in the house or waiting outside in the car that night. (See People v. Arrue (Dec. 21, 2007, B192064) [nonpub. opin.], p. 16 ["Regardless of whether defendant was merely a lookout or one of the assailants, this evidence demonstrates he knew that there was to be a robbery and that two of those involved were armed with guns"].) Under Banks, defendant argues, the special circumstance finding fails if he was the lookout in the car and not one of the assailants in the house. We agree.