chain.go
func chain(middlewares []func(http.Handler) http.Handler, endpoint http.Handler) http.Handler {
	// Return ahead of time if there aren't any middlewares for the chain
	if len(middlewares) == 0 {
		return endpoint
	}

	// Wrap the end handler with the middleware chain
	h := middlewares[len(middlewares)-1](endpoint)
	for i := len(middlewares) - 2; i >= 0; i-- {
		h = middlewares[i](h)
	}

	return h
}
func chain(middlewares []func(http.Handler) http.Handler, endpoint http.Handler) http.Handler {
	// Return ahead of time if there aren't any middlewares for the chain
	if len(middlewares) == 0 {
		return endpoint
	}

	// Wrap the end handler with the middleware chain
	h := middlewares[len(middlewares)-1](endpoint)
	for i := len(middlewares) - 2; i >= 0; i-- {
		h = middlewares[i](h)
	}

	return h
}
// chain builds a http.Handler composed of an inline middleware stack and endpoint
// handler in the order they are passed.