code: func FileMode(fm os.FileMode) PermissionBits {
  	perm := PermissionBits(fm.Perm())
  
  	if fm&os.ModeSetuid != 0 {
  		perm.SetSetuid(true)
  	}
  	if fm&os.ModeSetgid != 0 {
  		perm.SetSetgid(true)
  	}
  	if fm&os.ModeSticky != 0 {
  		perm.SetSticky(true)
  	}
  	return perm
  }
docs: // Given a FileMode from the os package, get it's permission bits