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: iter_str.go
    path of file: ./repos/plik/vendor/github.com/json-iterator/go
    
    the code of the file until where you have to start completion: package jsoniter

import (
	"fmt"
	"unicode/utf16"
)

// ReadString read string from iterator
func (iter *Iterator) ReadString() (ret string) {
	c := i
    
func (iter *Iterator) ReadString() (ret string) {
	c := iter.nextToken()
	if c == '"' {
		for i := iter.head; i < iter.tail; i++ {
			c := iter.buf[i]
			if c == '"' {
				ret = string(iter.buf[iter.head:i])
				iter.head = i + 1
				return ret
			} else if c == '\\' {
				break
			} else if c < ' ' {
				iter.ReportError("ReadString",
					fmt.Sprintf(`invalid control character found: %d`, c))
				return
			}
		}
		return iter.readStringSlowPath()
	} else if c == 'n' {
		iter.skipThreeBytes('u', 'l', 'l')
		return ""
	}
	iter.ReportError("ReadString", `expects " or n, but found `+string([]byte{c}))
	return
}