Finding the GPS seconds time from GPSDO

Hello

I'm Isaac. As it is said in this web: https://files.ettus.com/manual/page_gpsdo.html , get_mboard_sensor("gps_time") gives us the seconds since January 1, 1970 (so UTC seconds).

What I'm looking for is that GNU Radio gives me the GPS seconds directly (GPS time is ahead 18 seconds from UTC). Is there a method that gives us the GPS seconds?

Regards

Isaac T.