Thanks to the quick thinking of his sister, a 3-year-old Maine boy is doing OK after he swallowed a small battery.Gretchen Larkin, of Biddeford, Maine, said her son was playing with an electronic drawing pad when his sister came running to her.”She told me Colt swallowed a coin, and I was like, ‘Where did you find a coin?'” Larkin said.The coin turned out to