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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 load_keys(self, issuer, jwks_uri='', jwks=None, replace=False):
 """ Fetch keys from another server :param jwks_uri: A URL pointing to a site that will return a JWKS :param jwks: A dictionary representation of a JWKS :param issuer: The provider URL :param replace: If all previously gathered keys from this provider should be replace. :return: Dictionary with usage as key and keys as values """


        logger.debug("Initiating key bundle for issuer: %s" % issuer)

        if replace or issuer not in self.issuer_keys:
            self.issuer_keys[issuer] = []

        if jwks_uri:
            self.add_url(issuer, jwks_uri)
        elif jwks:
            # jwks should only be considered if no jwks_uri is present
            _keys = jwks['keys']
            self.issuer_keys[issuer].append(self.keybundle_cls(_keys))