code: public long getLastHeartbeatTime(String nodeID) {
  		if (this.nodeID.equals(nodeID)) {
  			return System.currentTimeMillis();
  		}
  		NodeDescriptor node = nodes.get(nodeID);
  		return node == null ? 0 : node.cpuWhen;
  	}
docs: --- GET LAST HEARTBEAT TIME OF A REMOTE NODE ---