Every year around the holidays, Pat Loomis & Friends come to the South End Library and get the joint clapping and cheering with their passionate  jazz performance. The teenage son of Loomis takes a turn at the horn. The cheers really take off. The hot chili, shopped for and cooked by  library staff and a spouse, is heaped on paper plates. Plastic forks and knives tick-tock at the edges of the library tables in synch with the rhythm. The chicken is gone before you know it. Patrons lean against bookshelves or sit on whatever chairs can be pulled around. It's that season, and we need this now, more than we ever thought. It's free, too. What are you waiting for..Tuesday night, December 18, 6:30 p.m.   See you there..