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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 register_identity(self, id_stmt):
 """Register `id_stmt` with its base identity, if any. """

        bst = id_stmt.search_one("base")
        if bst:
            bder = self.identity_deps.setdefault(bst.i_identity, [])
            bder.append(id_stmt)