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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 present(name,
            allocated_storage,
            db_instance_class,
            engine,
            master_username,
            master_user_password,
            db_name=None,
            storage_type=None,
            db_security_groups=None,
            vpc_security_group_ids=None,
            vpc_security_groups=None,
            availability_zone=None,
            db_subnet_group_name=None,
            preferred_maintenance_window=None,
            db_parameter_group_name=None,
            db_cluster_identifier=None,
            tde_credential_arn=None,
            tde_credential_password=None,
            storage_encrypted=None,
            kms_keyid=None,
            backup_retention_period=None,
            preferred_backup_window=None,
            port=None,
            multi_az=None,
            engine_version=None,
            auto_minor_version_upgrade=None,
            license_model=None,
            iops=None,
            option_group_name=None,
            character_set_name=None,
            publicly_accessible=None,
            wait_status=None,
            tags=None,
            copy_tags_to_snapshot=None,
            region=None,
            domain=None,
            key=None,
            keyid=None,
            monitoring_interval=None,
            monitoring_role_arn=None,
            domain_iam_role_name=None,
            promotion_tier=None,
            profile=None):
    '''
    Ensure RDS instance exists.

    name
        Name of the RDS state definition.

    allocated_storage
        The amount of storage (in gigabytes) to be initially allocated for the
        database instance.

    db_instance_class
        The compute and memory capacity of the Amazon RDS DB instance.

    engine
        The name of the database engine to be used for this instance. Supported
        engine types are: MySQL, mariadb, oracle-se1, oracle-se, oracle-ee, sqlserver-ee,
        sqlserver-se, sqlserver-ex, sqlserver-web, postgres and aurora. For more
        information, please see the ``engine`` argument in the Boto3 RDS
        `create_db_instance`_ documentation.

    master_username
        The name of master user for the client DB instance.

    master_user_password
        The password for the master database user. Can be any printable ASCII
        character except "/", '"', or "@".

    db_name
        The meaning of this parameter differs according to the database engine you use.
        See the Boto3 RDS documentation to determine the appropriate value for your configuration.
        https://boto3.readthedocs.io/en/latest/reference/services/rds.html#RDS.Client.create_db_instance

    storage_type
        Specifies the storage type to be associated with the DB instance.
        Options are standard, gp2 and io1. If you specify io1, you must also include
        a value for the Iops parameter.

    db_security_groups
        A list of DB security groups to associate with this DB instance.

    vpc_security_group_ids
        A list of EC2 VPC security group IDs to associate with this DB instance.

    vpc_security_groups
        A list of EC2 VPC security groups (IDs or Name tags) to associate with this DB instance.

    availability_zone
        The EC2 Availability Zone that the database instance will be created
        in.

    db_subnet_group_name
        A DB subnet group to associate with this DB instance.

    preferred_maintenance_window
        The weekly time range (in UTC) during which system maintenance can
        occur.

    db_parameter_group_name
        A DB parameter group to associate with this DB instance.

    db_cluster_identifier
        If the DB instance is a member of a DB cluster, contains the name of
        the DB cluster that the DB instance is a member of.

    tde_credential_arn
        The ARN from the Key Store with which the instance is associated for
        TDE encryption.

    tde_credential_password
        The password to use for TDE encryption if an encryption key is not used.

    storage_encrypted
        Specifies whether the DB instance is encrypted.

    kms_keyid
        If storage_encrypted is true, the KMS key identifier for the encrypted
        DB instance.

    backup_retention_period
        The number of days for which automated backups are retained.

    preferred_backup_window
        The daily time range during which automated backups are created if
        automated backups are enabled.

    port
        The port number on which the database accepts connections.

    multi_az
        Specifies if the DB instance is a Multi-AZ deployment. You cannot set
        the AvailabilityZone parameter if the MultiAZ parameter is set to true.

    engine_version
        The version number of the database engine to use.

    auto_minor_version_upgrade
        Indicates that minor engine upgrades will be applied automatically to
        the DB instance during the maintenance window.

    license_model
        License model information for this DB instance.

    iops
        The amount of Provisioned IOPS (input/output operations per second) to
        be initially allocated for the DB instance.

    option_group_name
        Indicates that the DB instance should be associated with the specified
        option group.

    character_set_name
        For supported engines, indicates that the DB instance should be
        associated with the specified CharacterSet.

    publicly_accessible
        Specifies the accessibility options for the DB instance. A value of
        true specifies an Internet-facing instance with a publicly resolvable
        DNS name, which resolves to a public IP address. A value of false
        specifies an internal instance with a DNS name that resolves to a
        private IP address.

    wait_status
        Wait for the RDS instance to reach a desired status before finishing
        the state. Available states: available, modifying, backing-up

    tags
        A dict of tags.

    copy_tags_to_snapshot
        Specifies whether tags are copied from the DB instance to snapshots of
        the DB instance.

    region
        Region to connect to.

    domain
        The identifier of the Active Directory Domain.

    key
        AWS secret key to be used.

    keyid
        AWS access key to be used.

    monitoring_interval
        The interval, in seconds, between points when Enhanced Monitoring
        metrics are collected for the DB instance.

    monitoring_role_arn
        The ARN for the IAM role that permits RDS to send Enhanced Monitoring
        metrics to CloudWatch Logs.

    domain_iam_role_name
        Specify the name of the IAM role to be used when making API calls to
        the Directory Service.

    promotion_tier
        A value that specifies the order in which an Aurora Replica is
        promoted to the primary instance after a failure of the existing
        primary instance. For more information, see Fault Tolerance for an
        Aurora DB Cluster .

    profile
        A dict with region, key and keyid, or a pillar key (string) that
        contains a dict with region, key and keyid.

    .. _create_db_instance: https://boto3.readthedocs.io/en/latest/reference/services/rds.html#RDS.Client.create_db_instance
    '''
    ret = {'name': name,
           'result': True,
           'comment': '',
           'changes': {}
           }

    r = __salt__['boto_rds.exists'](name, tags, region, key, keyid, profile)

    if not r.get('exists'):
        if __opts__['test']:
            ret['comment'] = 'RDS instance {0} would be created.'.format(name)
            ret['result'] = None
            return ret

        r = __salt__['boto_rds.create'](name, allocated_storage,
                                        db_instance_class, engine,
                                        master_username,
                                        master_user_password,
                                        db_name, db_security_groups,
                                        vpc_security_group_ids,
                                        vpc_security_groups,
                                        availability_zone,
                                        db_subnet_group_name,
                                        preferred_maintenance_window,
                                        db_parameter_group_name,
                                        backup_retention_period,
                                        preferred_backup_window,
                                        port, multi_az, engine_version,
                                        auto_minor_version_upgrade,
                                        license_model, iops,
                                        option_group_name,
                                        character_set_name,
                                        publicly_accessible, wait_status,
                                        tags, db_cluster_identifier,
                                        storage_type, tde_credential_arn,
                                        tde_credential_password,
                                        storage_encrypted, kms_keyid,
                                        domain, copy_tags_to_snapshot,
                                        monitoring_interval,
                                        monitoring_role_arn,
                                        domain_iam_role_name, region,
                                        promotion_tier, key, keyid, profile)

        if not r.get('created'):
            ret['result'] = False
            ret['comment'] = 'Failed to create RDS instance {0}.'.format(r['error']['message'])
            return ret

        ret['changes']['old'] = {'instance': None}
        ret['changes']['new'] = {
              'instance': __salt__['boto_rds.describe_db_instances'](
              name=name, jmespath='DBInstances[0]', region=region, key=key,
              keyid=keyid, profile=profile)}
        ret['comment'] = 'RDS instance {0} created.'.format(name)
    else:
        ret['comment'] = 'RDS instance {0} exists.'.format(name)
    return ret