The interval to merge with this interval.
std.datetime.date.DateTimeException if the two intervals do not intersect and are not adjacent or if this interval is empty.
assert(Interval!Date(Date(1996, 1, 2), Date(2012, 3, 1)).merge( PosInfInterval!Date(Date(1990, 7, 6))) == PosInfInterval!Date(Date(1990, 7 , 6))); assert(Interval!Date(Date(1996, 1, 2), Date(2012, 3, 1)).merge( PosInfInterval!Date(Date(2012, 3, 1))) == PosInfInterval!Date(Date(1996, 1 , 2)));
Returns the union of two intervals