This is tricky. You can't directly know if a bookmark has an action associated with it, and if so, what it is.
A round-about way of finding that out is to execute the bookmark (using the execute method) and then checking if it took you to a different page to what you were previously on. One possible catch is if the bookmarks happens to point to the same page you're on, but that can also be solved with some smart coding.
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