flipVerticalRange

import std.experimental.color;
enum RGB8 TheColor = RGB8(78, 82, 11);

MyTestImage!RGB8 test = new MyTestImage!RGB8(2, 2); 
test.fillOn(TheColor);

final class Foo {
    MyTestImage!RGB8 value;
    alias value this;

    this(MyTestImage!RGB8 value) {
        this.value = value;
    }
}

size_t count;
foreach(pixel; flipVerticalRange(test)) {
    assert(pixel.value == TheColor);
    count++;
}
assert(count == 4);

count = 0;
foreach(pixel; flipVerticalRange(test).flipVerticalRange()) {
    assert(pixel.value == TheColor);
    count++;
}
assert(count == 4);