t.Errorf("test.v flag (type %T) does not have IsBoolFlag method", f)
	} else if !bf.IsBoolFlag() {
		t.Error("test.v IsBoolFlag() returned false")
	}

	gf, ok := f.Value.(flag.Getter)
	if !ok {
		t.Fatalf("test.v flag (type %T) does not have Get method", f)
	}
	v := gf.Get()

	var want any
	switch *testFlagArg {
	case "":
		want = false
	case "-test.v":
		want = true
	case "-test.v=test2json":

		if x.Sign() != 0 && x.Cmp(priv.Q) < 0 {
			break
		}
	}

	priv.X = x
	priv.Y = new(big.Int)
	priv.Y.Exp(priv.G, x, priv.P)
	return nil
}

// fermatInverse calculates the inverse of k in GF(P) using Fermat's method.
// This has better constant-time properties than Euclid's method (implemented
// in math/big.Int.ModInverse) although math/big itself isn't strictly
// constant-time so it's not perfect.

00000010  b9 47 4b 47 49 af 52 88  3c 12 50 0d 65 46 f7 a1  |.GKGI.R.<.P.eF..|
00000020  50 39 c5 39 22 b3 45 e6  d3 25 44 a6 bc 3d bc 69  |P9.9".E..%D..=.i|
00000030  35 1d 61 cf a0 3c 53 77  94 67 66 ae 37 7f 3f 84  |5.a..<Sw.gf.7.?.|
00000040  17 03 03 00 17 5e 1d af  5b 7c b6 2d 19 ea 18 e0  |.....^..[|.-....|
00000050  55 47 43 e1 f2 0e 28 49  ae ef ba 86 17 03 03 00  |UGC...(I........|