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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 _make_regex(self):
 """ Compile rxp with all keys concatenated. """

        rxp = "|".join(
            map(self._address_rxp, self.keys()),
        )
        self._regex = re.compile(
            rxp,
            re.IGNORECASE,
        )