def _(): assert bf.quartiles([4, 2, 5, 3, 6, 1, 7]) == (1, 2, 4, 6, 7)
def _(): assert bf.quartiles([4, 5, 6, 1, 2, 3]) == (1, 2, 3.5, 5, 6)
def _(): assert bf.quartiles([1, 3, 2]) == (1, 1, 2, 3, 3)
def _(): assert bf.quartiles([2, 1]) == (1, None, 1.5, None, 2)
def _(): assert bf.quartiles([1]) == (1, 1, 1, 1, 1)
def _(): assert bf.quartiles([]) is None