A threatening briefcase in front of a mid-Wilshire lunch spot brought out helicopters, yellow tape and a dozen police cars Thursday afternoon.The restaurant is located directly across the street from Wilshire Courtyard, an office building that contains a number of entertainment offices including the Weinstein Co., E! and Variety. The activity centered on a briefcase left next to the tables and chairs in the outside eating area in front of Organic To Go. At 2:30, police appeared inside the Variety newsroom advising employees to remain at least 30 feet away from all windows. By three p.m., however, officers opened the briefcase and found it empty.