spinner.go
func (s *Spinner) UpdateCharSet(cs []string) {
	s.lock.Lock()
	defer s.lock.Unlock()
	s.chars = cs
}
func (s *Spinner) UpdateCharSet(cs []string) {
	s.lock.Lock()
	defer s.lock.Unlock()
	s.chars = cs
}
// UpdateCharSet will change the current character set to the given one