func NewIterator(reader io.Reader, unmarshaller RecordUnmarshaller) *Iterator {
	return &Iterator{
		reader:       reader,
		line:         0,
		scanner:      bufio.NewScanner(reader),
		unmarshaller: unmarshaller,
	}
}
func NewIterator(reader io.Reader, unmarshaller RecordUnmarshaller) *Iterator {
	return &Iterator{
		reader:       reader,
		line:         0,
		scanner:      bufio.NewScanner(reader),
		unmarshaller: unmarshaller,
	}
}
// NewIterator creates a CSVIterator from a Reader.