sequence.go
func (s *FileSequence) SetPadding(padChars string) {
	s.padChar = padChars
	s.zfill = s.padMapper.PaddingCharsSize(padChars)
}
func (s *FileSequence) SetPadding(padChars string) {
	s.padChar = padChars
	s.zfill = s.padMapper.PaddingCharsSize(padChars)
}
// Set a new padding characters for the sequence