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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 create_dbinstance_read_replica(self, id, source_id, instance_class=None, port=3306, availability_zone=None, auto_minor_version_upgrade=None):
 """ Create a new DBInstance Read Replica. :type id: str :param id: Unique identifier for the new instance. Must contain 1-63 alphanumeric characters. First character must be a letter. May not end with a hyphen or contain two consecutive hyphens :type source_id: str :param source_id: Unique identifier for the DB Instance for which this DB Instance will act as a Read Replica. :type instance_class: str :param instance_class: The compute and memory capacity of the DBInstance. Default is to inherit from the source DB Instance. Valid values are: * db.m1.small * db.m1.large * db.m1.xlarge * db.m2.xlarge * db.m2.2xlarge * db.m2.4xlarge :type port: int :param port: Port number on which database accepts connections. Default is to inherit from source DB Instance. Valid values [1115-65535]. Defaults to 3306. :type availability_zone: str :param availability_zone: Name of the availability zone to place DBInstance into. :type auto_minor_version_upgrade: bool :param auto_minor_version_upgrade: Indicates that minor engine upgrades will be applied automatically to the Read Replica during the maintenance window. Default is to inherit this value from the source DB Instance. :rtype: :class:`boto.rds.dbinstance.DBInstance` :return: The new db instance. """

        params = {'DBInstanceIdentifier' : id,
                  'SourceDBInstanceIdentifier' : source_id}
        if instance_class:
            params['DBInstanceClass'] = instance_class
        if port:
            params['Port'] = port
        if availability_zone:
            params['AvailabilityZone'] = availability_zone
        if auto_minor_version_upgrade is not None:
            if auto_minor_version_upgrade is True:
                params['AutoMinorVersionUpgrade'] = 'true'
            else:
                params['AutoMinorVersionUpgrade'] = 'false'

        return self.get_object('CreateDBInstanceReadReplica',
                               params, DBInstance)