>
> f a (f b (f c (f d (f e z))))
>
-> The left fold on the other hand starts combining `z` with elements from the left. `f z z` is then combined with `b`, and so on:
+> The left fold on the other hand starts combining `z` with elements from the left. `f z a` is then combined with `b`, and so on:
>
> f (f (f (f (f z a) b) c) d) e
>