public void TestField_Mult()
        {
            Assert.Equal(9, HashiCorpShamir.Mult(3, 7));

            Assert.Equal(0, HashiCorpShamir.Mult(3, 0));

            Assert.Equal(0, HashiCorpShamir.Mult(0, 3));
        }
        public void TestPolynomial_Eval()
        {
            var p = HashiCorpShamir.MakePolynomial(42, 1);

            Assert.Equal(42, p.Evaluate(0));

            // out := p.evaluate(1)
            // exp := add(42, mult(1, p.coefficients[1]))
            // if out != exp {
            //     t.Fatalf("bad: %v %v %v", out, exp, p.coefficients)
            // }

            var ret = p.Evaluate(1);
            var exp = HashiCorpShamir.Add(42,
                                          HashiCorpShamir.Mult(1, p.Coefficients[1]));

            Assert.Equal(ret, exp);
        }