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: request.go
    path of file: ./repos/zinx/znet
    
    the code of the file until where you have to start completion: package znet

import (
	"math"
	"sync"

	"github.com/aceld/zinx/zconf"
	"github.com/aceld/zinx/ziface"
	"github.com/aceld/zinx/zpack"
)

const (
	PRE_HANDLE 
    
func NewRequest(conn ziface.IConnection, msg ziface.IMessage) ziface.IRequest {
	req := new(Request)
	req.steps = PRE_HANDLE
	req.conn = conn
	req.msg = msg
	req.stepLock = new(sync.RWMutex)
	req.needNext = true
	req.index = -1
	return req
}