public void Try_to_return_part_of_a()
{
var a = Sigo.Create(7,
"x/name", "Phat"
).Freeze();
var b = Sigo.Create(7,
"x/name", "Phat",
"y", "y"
).Freeze();
var r = ImplMergeSpec.Merge(a, b);
// r equal b...
SigoAssert.Equal(r, b);
// ...but not same b...
SigoAssert.NotSame(r, b);
// ...because there is r[x] == a[x]
SigoAssert.Equal(r["x"], a["x"]);
SigoAssert.Same(r["x"], a["x"]);
}