Determining if a server is clustered or stand-alone

I'm in the process of writing a powershell script to inventory my SQL Server environment. In collecting the server information, I'd like to grab the physical hostnames that make up any clustered environments. I know I can use $nodes=get-clusternode -Cluster SERVERNAME |select nameto get the physical servers in the cluster, but if I run that on a non-clustered server, I get an error, obviously. So, can someone recommend a good way to determine whether the SERVERNAME I've connected to is a cluster resource group or a physical stand-alone server?