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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 _add_method_setting(self, conn, api_id, stage_name, path, key, value, op):
 """ Update a single method setting on the specified stage. This uses the 'add' operation to PATCH the resource. :param conn: APIGateway API connection :type conn: :py:class:`botocore:APIGateway.Client` :param api_id: ReST API ID :type api_id: str :param stage_name: stage name :type stage_name: str :param path: path to patch (see https://docs.aws.amazon.com/apigateway/\ api-reference/resource/stage/#methodSettings) :type path: str :param key: the dictionary key this should update :type key: str :param value: new value to set :param op: PATCH operation to perform, 'add' or 'replace' :type op: str """

        logger.debug('update_stage PATCH %s on %s; value=%s',
                     op, path, str(value))
        res = conn.update_stage(
            restApiId=api_id,
            stageName=stage_name,
            patchOperations=[
                {
                    'op': op,
                    'path': path,
                    'value': str(value)
                }
            ]
        )
        if res['methodSettings']['*/*'][key] != value:
            logger.error('methodSettings PATCH expected to update %s to %s,'
                         'but instead found value as %s', key, value,
                         res['methodSettings']['*/*'][key])
        else:
            logger.info('Successfully updated methodSetting %s to %s',
                        key, value)