A false midnight

However, the comparison to a float where every int is false is not exactly a fair comparison since a datetime is always True. Compare instead to a Decimal implemented as a pair: (DecimalIntPart, DecimalFractionalPart). Then making the DecimalFractionalPart be False when the Decimal is an integer is much more reasonable:

if my_decimal.fractional_part: print("Is not an integer")

It, to me, makes the original implementation seem less "completely insane" and more "not the best choice".