<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def is_cluster_ssh_available(cluster_instances, opts):
 """ Check if SSH is available on all the instances in a cluster. """

    for i in cluster_instances:
        dns_name = get_dns_name(i, opts.private_ips)
        if not is_ssh_available(host=dns_name, opts=opts):
            return False
    else:
        return True