scope (global) [
[Bar]             : {t : Foo}
    [vertex__vs_main] : ()
[Foo]             : {color : float4}
    scope (Foo) [
        [color]           : float4
    ]
    scope (Bar) [
        [t]               : Foo
    ]
    scope (vertex__vs_main) [
        [b]               : Bar
        [f]               : Foo
    ]
]
