code: func (gce *Cloud) DescribeSnapshot(snapshotToGet string) (status string, isCompleted bool, err error) {
  	snapshot, err := gce.getSnapshotByName(snapshotToGet)
  	if err != nil {
  		return "", false, err
  	}
  	//no snapshot is found
  	if snapshot == nil {
  		return "", false, fmt.Errorf("snapshot %s is not found", snapshotToGet)
  	}
  	if snapshot.Status == "READY" {
  		return snapshot.Status, true, nil
  	}
  	return snapshot.Status, false, nil
  }
docs: // DescribeSnapshot checks the status of a snapshot