How to enable MultiAZ for an RDS Instance using Boto3?

I wanted to enable the multi-az feature for an rds instance using Boto3.But it is not getting done by using the script.Also I updated my policy for rds instances but still it is not getting updated.I am using the following script.

    modified_rds_attributes = rds_conn_boto3.modify_db_instance(DBInstanceIdentifier=id, MultiAZ=True).