OptionalallGive 1 instead of 0 left of the first point and N - 1 instead of N at or right of the last (N = vec.length).
OptionalleftIntervals (v_i, v_(i+1)] instead of [v_i, v_(i+1)).
OptionalrightmostTreat the last interval as closed on the right (with leftOpen, the first as closed on the left).
Options for findInterval.