There’s a typo in DLS Course 4 Week 3 A1.

In “Exercise 2 - iou” description it’s mentioned that:

For this exercise, a box is defined using its two corners:

**upper left** (𝑥1,𝑦1) and **lower right** (𝑥2,𝑦2)…

then in the unit test we can see:

Test case 1: boxes intersect

box1 = (2, 1, 4, 3)

box2 = (1, 2, 3, 4)

which means that:

(𝑥1,𝑦1) is **lower left** and (𝑥2,𝑦2) is **upper right** corner.