code: func (c *Client) AddonInfo(appIdentity string, addonIdentity string) (*Addon, error) {
  	var addon Addon
  	return &addon, c.Get(&addon, "/apps/"+appIdentity+"/addons/"+addonIdentity)
  }
docs: // Info for an existing add-on.
  //
  // appIdentity is the unique identifier of the Addon's App. addonIdentity is the
  // unique identifier of the Addon.