public void Toggle_is_SymmetricExcept()
{
CKTrait m = Context.FindOrCreate( "Beta+Alpha+Fridge+Combo" );
Assert.That( m.SymmetricExcept( Context.FindOrCreate( "Beta" ) ).ToString() == "Alpha+Combo+Fridge" );
Assert.That( m.SymmetricExcept( Context.FindOrCreate( "Fridge+Combo" ) ).ToString() == "Alpha+Beta" );
Assert.That( m.SymmetricExcept( Context.FindOrCreate( "Beta+Fridge+Combo" ) ).ToString() == "Alpha" );
Assert.That( m.SymmetricExcept( Context.FindOrCreate( "Beta+Fridge+Combo+Alpha" ) ).ToString() == "" );
Assert.That( m.SymmetricExcept( Context.FindOrCreate( "" ) ).ToString() == "Alpha+Beta+Combo+Fridge" );
Assert.That( m.SymmetricExcept( Context.FindOrCreate( "Xtra" ) ).ToString() == "Alpha+Beta+Combo+Fridge+Xtra" );
Assert.That( m.SymmetricExcept( Context.FindOrCreate( "Alpha+Xtra" ) ).ToString() == "Beta+Combo+Fridge+Xtra" );
Assert.That( m.SymmetricExcept( Context.FindOrCreate( "Zenon+Alpha+Xtra+Fridge" ) ).ToString() == "Beta+Combo+Xtra+Zenon" );
}