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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def find_bookmark_file ():
 """Return the bookmark file of the Opera profile. Returns absolute filename if found, or empty string if no bookmark file could be found. """

    try:
        dirname = get_profile_dir()
        if os.path.isdir(dirname):
            for name in OperaBookmarkFiles:
                fname = os.path.join(dirname, name)
                if os.path.isfile(fname):
                    return fname
    except Exception:
        pass
    return u""