perl -MDateTime -E'
say DateTime->new(time_zone=>"UTC",year=>1972,month=>12,day=>31,hour=>23,minute=>59,second=>60)->add(months=>$_)->month_name for (0,1);
'
December
February

##</code><code>##

perl -MDateTime -E'
say DateTime->new(time_zone=>"UTC",year=>2015,month=>6,day=>30,hour=>23,minute=>59,second=>60)->add(months=>$_)->month_name for (0,1);
'
June
July


##</code><code>##