func ListSpec(cli bce.Client) (*ListSpecResult, error) {
	req := &bce.BceRequest{}
	req.SetUri(getSpecUri())
	req.SetMethod(http.GET)
	resp := &bce.BceResponse{}
	if err := cli.SendRequest(req, resp); err != nil {
		return nil, err
	}
	if resp.IsFail() {
		return nil, resp.ServiceError()
	}
	jsonBody := &ListSpecResult{}
	if err := resp.ParseJsonBody(jsonBody); err != nil {
		return nil, err
	}
	return jsonBody, nil
}
ListSpec - get specification list information of the instance

PARAMS:
- cli: the client agent which can perform sending request
RETURNS:
- *ListSpecResult: result of the specifications
- error: nil if success otherwise the specific error
package api
import (
	"encoding/json"
	"github.com/baidubce/bce-sdk-go/bce"
	"github.com/baidubce/bce-sdk-go/http"
)