Convenience to string method.

def device_time_str(self, resp, indent="  "):
        """Convenience to string method.
        """
        time = resp.time
        uptime = resp.uptime
        downtime = resp.downtime
        time_s = datetime.datetime.utcfromtimestamp(time/1000000000) if time != None else None
        uptime_s = round(nanosec_to_hours(uptime), 2) if uptime != None else None
        downtime_s = round(nanosec_to_hours(downtime), 2) if downtime != None else None
        s = "Current Time: {} ({} UTC)\n".format(time, time_s)
        s += indent + "Uptime (ns): {} ({} hours)\n".format(uptime, uptime_s)
        s += indent + "Last Downtime Duration +/-5s (ns): {} ({} hours)\n".format(downtime, downtime_s)
        return s