Delete duplicate function: create_multi_devices_program, it is same as program.create_multi_devices_program

CUDA_VISIBLE_DEVICES 默认值必须为str, 否则split会报错

add a  file separator, it mainly  to avoid  missing the file path separator in yml

add a necessary check for checkpoints, if you miss the file prefix and it will not execute the checkpoints codes

remove the  useless parameters  and  update import