func (s *FileSequence) End() int {
	if s.frameSet == nil {
		return 0
	}
	return s.frameSet.End()
}
func (s *FileSequence) End() int {
	if s.frameSet == nil {
		return 0
	}
	return s.frameSet.End()
}
// End returns the ending frame of the sequence.
// If a frame range/number could not be parsed, then this
// will always return 0