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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 identifier(self):
 """The author's ID. Might differ from the one provided."""

        ident = self._json['coredata']['dc:identifier'].split(":")[-1]
        if ident != self._id:
            text = "Profile with ID {} has been merged and the new ID is "\
                   "{}.  Please update your records manually.  Files have "\
                   "been cached with the old ID.".format(self._id, ident)
            warn(text, UserWarning)
        return ident