private static void HexAssertValid(this string thisObj, int sizeInBits)
{
thisObj.NonEmptyAssertValid();
(sizeInBits % 8).Should().Be(0, $"sizeInBits should be divisible by 8 but sizeInBits is {sizeInBits}");
var numHexChars = sizeInBits / 8 * 2;
var because =
$"String should be {numHexChars} hex digits ({sizeInBits}-bits) but the actual value is `{thisObj}' (length: {thisObj.Length})";
thisObj.Length.Should().Be(numHexChars, because); // 2 hex chars per byte
TraceContext.IsHex(thisObj).Should().BeTrue(because);
}
