Why does the Heap Library by James Harton sort the elements in a different manner from a normal min-heap?

Hi! So I was exploring some libraries of Elixir and I came across this heap library by James Harton.

The thing which I wanted to ask is that behind the scenes, the result produced by this is quite different from a normal min-heap. For example, I push the following elements to my heap: [4, 8, 9]. Then, I pop the first element and push 11 which gives us: [8, 9, 11]. Similarly, I again pop the topmost element and push 20. Once again, I pop the topmost element and push 15 this time.

My final heap in a normal min-heap would look like: [11, 20, 15]. However, when using the library, my result comes out to be [11, 15, 20].

If anyone has used this library and is familiar with it, does anyone know the reason why this is the case? And is there any way of getting the normal min-heap results? I also tried using the Heap.min() part of this library as well, however, that doesn’t work as well.