Page generators can be iterated over multiple times when expected to be empty and stop after the first time. The following iterations can contain erratic results.
For example: It is possible to iterate over a generator with a for loop and then iterate over that same generator with a later for loop.
If the generator is called multiple times without `step` specified, the generator repeats itself if iterated over again. If `step` is specified, the generator shifts results erratically when called multiple times.
Below is REPL output from the `test:test` site using `PrefixingPageGenerator()`.
```
>>> ppg = PrefixingPageGenerator('a', step=2, total=3)
>>> for _ in range(3):
... print list(ppg)
...
[Page(A), Page(AAA), Page(AF Test)]
[Page(AF Test), Page(AKlapper2), Page(API output)]
[Page(AKlapper2), Page(API output), Page(API page move test)]
```
Expected output would be `[]` after the first one.