Get information about DB Snapshots.

        :type snapshot_id: str
        :param snapshot_id: The unique identifier of an RDS snapshot.
                            If not provided, all RDS snapshots will be returned.

        :type instance_id: str
        :param instance_id: The identifier of a DBInstance.  If provided,
                            only the DBSnapshots related to that instance will
                            be returned.
                            If not provided, all RDS snapshots will be returned.

        :type max_records: int
        :param max_records: The maximum number of records to be returned.
                            If more results are available, a MoreToken will
                            be returned in the response that can be used to
                            retrieve additional records.  Default is 100.

        :type marker: str
        :param marker: The marker provided by a previous request.

        :rtype: list
        :return: A list of :class:`boto.rds.dbsnapshot.DBSnapshot`

def get_all_dbsnapshots(self, snapshot_id=None, instance_id=None,
                            max_records=None, marker=None):
        """
        Get information about DB Snapshots.

        :type snapshot_id: str
        :param snapshot_id: The unique identifier of an RDS snapshot.
                            If not provided, all RDS snapshots will be returned.

        :type instance_id: str
        :param instance_id: The identifier of a DBInstance.  If provided,
                            only the DBSnapshots related to that instance will
                            be returned.
                            If not provided, all RDS snapshots will be returned.

        :type max_records: int
        :param max_records: The maximum number of records to be returned.
                            If more results are available, a MoreToken will
                            be returned in the response that can be used to
                            retrieve additional records.  Default is 100.

        :type marker: str
        :param marker: The marker provided by a previous request.

        :rtype: list
        :return: A list of :class:`boto.rds.dbsnapshot.DBSnapshot`
        """
        params = {}
        if snapshot_id:
            params['DBSnapshotIdentifier'] = snapshot_id
        if instance_id:
            params['DBInstanceIdentifier'] = instance_id
        if max_records:
            params['MaxRecords'] = max_records
        if marker:
            params['Marker'] = marker
        return self.get_list('DescribeDBSnapshots', params,
                             [('DBSnapshot', DBSnapshot)])