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

import (
	"encoding/json"
	"io"
	"reflect"
	"sync"
	"unsafe"

	"github.com/modern-go/concurrent"
	"github.com/modern-go/reflect2"
)

// Config customize how the API should behave.
// The API is created from Config by Froze.
type Config struct {
	IndentionStep                 int
	MarshalFloatWith6Digits       bool
	EscapeHTML                    bool
	SortMapKeys      
    
func (cfg *frozenConfig) useNumber(extension DecoderExtension) {
	extension[reflect2.TypeOfPtr((*interface{})(nil)).Elem()] = &funcDecoder{func(ptr unsafe.Pointer, iter *Iterator) {
		exitingValue := *((*interface{})(ptr))
		if exitingValue != nil && reflect.TypeOf(exitingValue).Kind() == reflect.Ptr {
			iter.ReadVal(exitingValue)
			return
		}
		if iter.WhatIsNext() == NumberValue {
			*((*interface{})(ptr)) = json.Number(iter.readNumberAsString())
		} else {
			*((*interface{})(ptr)) = iter.Read()
		}
	}}
}