Reduced Premature Mortality in Rwanda: Lessons From Success (British Medical Journal, P. Farmer, C. Nutt, C. Wagner, C. Sekabaraga, T. Nuthulaganti, J. Weigel, D. Bertrand Farmer, A. Habinshuti, S. Dusabeyesu Mugeni, J-C. Karasi, and P. Drobac)