By Jonathan Allen (Reuters) -Alabama offered assistance on Friday to other U.S. states seeking to carry out executions using asphyxiation by nitrogen gas, a few hours after pioneering the new method to kill Kenneth Smith, a prisoner condemned for a 1988 murder. The state also promised more to come in Alabama: Attorney General Steve Marshall said 43 other people on death row had chosen asphyxiation over lethal injections since lawmakers approved the method in 2018. Alabama called the new method “humane,” while human rights groups condemned it as cruel and torturous. A spokesperson for U.S. Pres…