public void IntervalClosedContains()
        {
            Interval ac = Interval.FromEndpoints(a, c);

            Assert.IsTrue(ac.ClosedContains(a));
            Assert.IsTrue(ac.ClosedContains(c));
            Assert.IsTrue(ac.ClosedContains(b));
            Assert.IsFalse(ac.ClosedContains(d));
        }