withAdditionalIntervals

alias Interval = Tuple!(size_t, "begin", size_t, "end");

auto mask = masker!(
    "a.begin",
    "a.end",
    level => level >= 2 ? 1 : 0,
)(
    [
        Interval(1, 5),
        Interval(6, 7),
        Interval(9, 10),
    ],
    [Interval(0, 10)]
);

alias I = mask.FrontType;
assert(equal(mask.save, [I(0, 10, 0)]));

auto intersection1 = mask.withAdditionalIntervals([Interval(4, 7)]);
assert(equal(
    intersection1,
    [
        I(0, 4, 0),
        I(4, 5, 1),
        I(5, 6, 0),
        I(6, 7, 1),
        I(7, 10, 0),
    ]
), investigateMask(mask, "mask does not match"));

auto intersection2 = mask.withAdditionalIntervals([Interval(8, 10)]);
assert(equal(
    intersection2,
    [
        I(0, 9, 0),
        I(9, 10, 1),
    ]
), investigateMask(mask, "mask does not match"));