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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 truncate_to_issuer(self, cert):
 """ Remove all certificates in the path after the issuer of the cert specified, as defined by this path :param cert: An asn1crypto.x509.Certificate object to find the issuer of :raises: LookupError - when the issuer of the certificate could not be found :return: The current ValidationPath object, for chaining """


        issuer_index = None
        for index, entry in enumerate(self):
            if entry.subject == cert.issuer:
                if entry.key_identifier and cert.authority_key_identifier:
                    if entry.key_identifier == cert.authority_key_identifier:
                        issuer_index = index
                        break
                else:
                    issuer_index = index
                    break

        if issuer_index is None:
            raise LookupError('Unable to find the issuer of the certificate specified')

        while len(self) > issuer_index + 1:
            self.pop()

        return self