If a police officer's opinion based on the officer's years of experience and training is classified as expert opinion testimony, how does the prosecution satisfy the burden imposed by Rule 702 that the officer is "qualified" as an expert? Why was it important to the prosecution in People v. Clifton, 750 N.E.2d 686 (Ill. App. 2001) [Case No. 1982126] to offer expert testimony on the workings of the internal leadership of the Gangster Disciples gang? Do you agree with the court's reasoning and decision?