shlex.go
func NewTokenizer(r io.Reader) *Tokenizer {
	input := bufio.NewReader(r)
	classifier := newDefaultClassifier()
	return &Tokenizer{
		input:      *input,
		classifier: classifier}
}
func NewTokenizer(r io.Reader) *Tokenizer {
	input := bufio.NewReader(r)
	classifier := newDefaultClassifier()
	return &Tokenizer{
		input:      *input,
		classifier: classifier}
}
// NewTokenizer creates a new tokenizer from an input stream.