code: func (d Device) MemoryInfo() (uint64, uint64, error) {
  	if C.nvmlHandle == nil {
  		return 0, 0, errLibraryNotLoaded
  	}
  	var memory C.nvmlMemory_t
  	r := C.nvmlDeviceGetMemoryInfo(d.dev, &memory)
  	return uint64(memory.total), uint64(memory.used), errorString(r)
  }
docs: // MemoryInfo returns the total and used memory (in bytes) of the device.