Duin: Man takes time to explain life to teenage girl B ecause physician-assisted suicide is a subject that far too often divides families and traumatizes the best of friends, perhaps there is something to be gained in eavesdropping for a moment on a conversation about life and death between total strangers. Caleb Heppner is a retired child-welfare administrator in Salem with terminal cancer, Rebekah Puddington a high school freshman in rural upstate New York. They will, most likely, never meet in person, but their paths crossed one night last October. Bekah was watching the nightly news with her father, a...