public static ColumnFamily removeDeletedCF(ColumnFamily cf,int gcBefore){
  cf.purgeTombstones(gcBefore);
  return !cf.hasColumns() && !cf.isMarkedForDelete() ? null : cf;
}

public static ColumnFamily removeDeletedCF ( ColumnFamily cf , int gcBefore ) { cf . purgeTombstones ( gcBefore ) ; return ! cf . hasColumns ( ) && ! cf . isMarkedForDelete ( ) ? null : cf ; }
purges gc - able top - level and range tombstones , returning ` cf ` if there are any columns or tombstones left , null otherwise .
