* `activate` Boolean - `true` to bring the opened application to the
foreground. The default is `true`.
* `callback` Function (optional) - If specified will perform the open asynchronously. _macOS_
- * `opened` Boolean
+ * `error` Error
Returns `Boolean` - Whether an application was available to open the URL.
-If callback is specified, it will return whether it was able to initiate the open call.
+If callback is specified, always returns true.
Open the given external protocol URL in the desktop's default manner. (For
example, mailto: URLs in the user's default mail agent).