code: func (c *Client) SnapshotServer(identifier string) (*Image, error) {
  	res, err := c.MakeApiRequest("POST", "/1.0/servers/"+identifier+"/snapshot", nil, nil)
  	if err != nil {
  		return nil, err
  	}
  	imageID := getLinkRel(res.Header.Get("Link"), "img", "snapshot")
  	if imageID != nil {
  		img := new(Image)
  		img.Id = *imageID
  		return img, nil
  	}
  	return nil, nil
  }
docs: // SnapshotServer issues a request to snapshot the disk of an existing
  // server. The snapshot is allocated an Image Id which is returned within an
  // instance of Image.