How to use the flintrock.ec2.EC2Cluster function in Flintrock

])
            .create_tags(Tags=master_tags))

        slave_tags = [
            {'Key': 'flintrock-role', 'Value': 'slave'},
            {'Key': 'Name', 'Value': '{c}-slave'.format(c=cluster_name)}]
        slave_tags += tags

        (ec2.instances
            .filter(
                Filters=[
                    {'Name': 'instance-id', 'Values': [i.id for i in slave_instances]}
                ])
            .create_tags(Tags=slave_tags))

        cluster = EC2Cluster(
            name=cluster_name,
            region=region,
            vpc_id=vpc_id,
            ssh_key_pair=generate_ssh_key_pair(),
            master_instance=master_instance,
            slave_instances=slave_instances)

        cluster.wait_for_state('running')

        provision_cluster(
            cluster=cluster,
            services=services,
            user=user,
            identity_file=identity_file)

        return cluster

def _compose_cluster(*, name: str, region: str, vpc_id: str, instances: list) -> EC2Cluster:
    """
    Compose an EC2Cluster object from a set of raw EC2 instances representing
    a Flintrock cluster.
    """
    (master_instance, slave_instances) = _get_cluster_master_slaves(instances)

    cluster = EC2Cluster(
        name=name,
        region=region,
        vpc_id=vpc_id,
        master_instance=master_instance,
        slave_instances=slave_instances)

    return cluster