code: func Register(name string, factory StorageDriverFactory) {
  	if factory == nil {
  		panic("Must not provide nil StorageDriverFactory")
  	}
  	_, registered := driverFactories[name]
  	if registered {
  		panic(fmt.Sprintf("StorageDriverFactory named %s already registered", name))
  	}
  
  	driverFactories[name] = factory
  }
docs: // Register makes a storage driver available by the provided name.
  // If Register is called twice with the same name or if driver factory is nil, it panics.
  // Additionally, it is not concurrency safe. Most Storage Drivers call this function
  // in their init() functions. See the documentation for StorageDriverFactory for more.