I’d argue it should be shiftBy rather than advanceBy to deal with negative periods, but yes. The issue here is the conflation of summing periods (commutative an

I’d argue it should be shiftBy rather than advanceBy to deal with negative periods, but yes. The issue here is the conflation of summing periods (commutative and associative) with shifting a date by a certain period. None of the proposed names in the post actually clarify anything - they merely make the behavior seem more confusing.