code: func Overlay2Supported(kernelVersion string) bool {
  	if !overlayFSSupported() {
  		return false
  	}
  
  	daemonV, err := kernel.ParseRelease(kernelVersion)
  	if err != nil {
  		return false
  	}
  	requiredV := kernel.VersionInfo{Kernel: 4}
  	return kernel.CompareKernelVersion(*daemonV, requiredV) > -1
  
  }
docs: // Overlay2Supported returns true if the current system supports overlay2 as graphdriver