You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: parser.go
    path of file: ./repos/delve/vendor/github.com/cosiner/argv
    
    the code of the file until where you have to start completion: package argv

import (
	"errors"
	"fmt"
	"os"
)

type (
	Expander func(string) (string, error)

	// Parser take tokens from Scanner, and do syntax checking, and generate the splitted argum
    
func (p *Parser) multipleUnit() ([]Token, bool, error) {
	var (
		toks []Token
	)
	for {
		tok, ok, err := p.unit()
		if err != nil {
			return nil, false, err
		}
		if !ok {
			break
		}
		toks = append(toks, tok)
	}
	return toks, len(toks) > 0, nil
}