ctx.go
func (ctx *ReqCtx) Next() error {
	ctx.mwIndex++

	// call next middleware in the stack, if any
	if ctx.mwIndex <= len(ctx.mw) {
		return ctx.mw[ctx.mwIndex-1](ctx)
	}

	return nil
}
func (ctx *ReqCtx) Next() error {
	ctx.mwIndex++

	// call next middleware in the stack, if any
	if ctx.mwIndex <= len(ctx.mw) {
		return ctx.mw[ctx.mwIndex-1](ctx)
	}

	return nil
}
// Next executes the next middleware in the middleware stack.