sequence.go
func FindSequencesOnDisk(path string, opts ...FileOption) (FileSequences, error) {
	return findSequencesOnDisk(path, opts...)
}
func FindSequencesOnDisk(path string, opts ...FileOption) (FileSequences, error) {
	return findSequencesOnDisk(path, opts...)
}
// FindSequencesOnDisk searches a given directory path and
// sorts all valid sequence-compatible files into a list of
// FileSequences
//
// By default, only non-hidden sequences of files will be returned.
// Extra FileOption values may be given to control whether things like
// hidden files, or single (non-sequence) files should be included in
// the search results.
//
// If there are any errors reading the directory or the files,
// a non-nil error will be returned.