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: reader.go
    path of file: ./repos/mal/impls/go/src/reader
    
    the code of the file until where you have to start completion: package reader

import (
	"errors"
	"regexp"
	"strconv"
	"strings"
	//"fmt"
)

import (
	. "types"
)

type Reader interface {
	next() *string
	peek() *string
}

type Token
    
func tokenize(str string) []string {
	results := make([]string, 0, 1)
	// Work around lack of quoting in backtick
	re := regexp.MustCompile(`[\s,]*(~@|[\[\]{}()'` + "`" +
		`~^@]|"(?:\\.|[^\\"])*"?|;.*|[^\s\[\]{}('"` + "`" +
		`,;)]*)`)
	for _, group := range re.FindAllStringSubmatch(str, -1) {
		if (group[1] == "") || (group[1][0] == ';') {
			continue
		}
		results = append(results, group[1])
	}
	return results
}