code: func CheckSystemDriveAndRemoveDriveLetter(path string) (string, error) {
  	if len(path) == 2 && string(path[1]) == ":" {
  		return "", fmt.Errorf("No relative path specified in %q", path)
  	}
  	if !filepath.IsAbs(path) || len(path) < 2 {
  		return filepath.FromSlash(path), nil
  	}
  	if string(path[1]) == ":" && !strings.EqualFold(string(path[0]), "c") {
  		return "", fmt.Errorf("The specified path is not on the system drive (C:)")
  	}
  	return filepath.FromSlash(path[2:]), nil
  }
docs: // CheckSystemDriveAndRemoveDriveLetter verifies and manipulates a Windows path.
  // This is used, for example, when validating a user provided path in docker cp.
  // If a drive letter is supplied, it must be the system drive. The drive letter
  // is always removed. Also, it translates it to OS semantics (IOW / to \). We
  // need the path in this syntax so that it can ultimately be contatenated with
  // a Windows long-path which doesn't support drive-letters. Examples:
  // C:			--> Fail
  // C:\			--> \
  // a			--> a
  // /a			--> \a
  // d:\			--> Fail