You can download assemble_superand.py here.
python assemble_superand.py -c <config> <nor>.bin <nand>.bin output_dir
Example Command:
python assemble_superand.py -c 913SH 821SH_S98WS01GPGGFW002-f1f2.bin 821SH_S98WS01GPGGFW002-n_data.bin output
Configs
Any config will work for the phone it is named after. Additional phones compatible with the config are listed below.