code: func (c *Client) ListVersions(i *ListVersionsInput) ([]*Version, error) {
  	if i.Service == "" {
  		return nil, ErrMissingService
  	}
  
  	path := fmt.Sprintf("/service/%s/version", i.Service)
  	resp, err := c.Get(path, nil)
  	if err != nil {
  		return nil, err
  	}
  
  	var e []*Version
  	if err := decodeJSON(&e, resp.Body); err != nil {
  		return nil, err
  	}
  	sort.Sort(versionsByNumber(e))
  
  	return e, nil
  }
docs: // ListVersions returns the full list of all versions of the given service.