func (self DiskImageExistsState) Assess(instance instanceTypes.BaseInstance) bool {
	if instance.Type == instanceTypes.VM {
		if _, err := os.Stat(instance.GetDiskImageFileName()); err == nil {
			return true
		}
	}
	return false
}
func (self DiskImageExistsState) Enforce(instance instanceTypes.BaseInstance) {
	if _, fileErr := os.Stat(instance.GetDiskImageFileName()); os.IsNotExist(fileErr) {

		imageSizeString := string(instance.RootDiskImageSize) + "GB"

		imageFileName := instance.GetDiskImageFileName()

		fmt.Printf("imageSizeString: %s\n", imageSizeString)
		fmt.Printf("imageFileName: %s\n", imageFileName)

		cmd := exec.Command("truncate", "-s", imageSizeString, instance.GetDiskImageFileName())

		cmdErr := cmd.Run()

		if cmdErr != nil {
			fmt.Printf("ERROR: %s\n", cmdErr)
		}
	}
}