flatten()

Creates a Dictionary from all of the keys available in all layers of the Config object.Each key is paired with the value from the topmost layer that has that key. The dictionary returns the same values for each key as one would get from the Config’s get(key:) -> AnyObject? method. If you don’t need the underlying layers of a Config once it has been assembled, this can be a performance gain, as accessing a native Swift Dictionary is likely to be faster than Config.get.