healpixRingToNest( k, ringIndex )Note: the ringIndex parameter is 0-based,
unlike the table row index special token $index
(a.k.a. $0), which is 1-based.
So if the HEALpix index is implicitly determined by the table row,
the value $index-1 should be used.
k (integer)ringIndex (long integer)long healpixRingToNest(int, long)