fastboot set_active command does not exist

How to automate slot selection after android AB-Update fastboot change slot Fastboot firmware, ZIP firmware is official from Xiaomi EU ROM, TWRP and Card slot microSDXC Internal 64GB 4GB RAM, 64GB 6GB RAM fastboot_ error_ failed to identify current slot 8GB MEMORY Built-in Wifi Built-in Camera with NumPad Flat Keyboard VGA SLOT HDMI SLOT SD CARD SLOT DVD DRIVE USBLAN PORT

fastboot change slot  It can be very useful to know if partition slot A or slot B is currently active and you can learn