REST API pagination with a "nextToken" - how to iterate through pages

Hello,

I am an beginner/intermediate-level Power User, and am new to accessing APIs through Power Query. I am feeling pretty confident today - I have successfully fetched the bearer token for my API and made several successful API calls for various data. I am stuck on the next part of the puzzle.

The API I am accessing limits results to 100 per page, so I will need to fetch multiple pages of results and then merge them together into a single query. The tricky part is that *if* there is a next page, the API returns a token called "nextToken" to indicate that there is a next page, and that token must be fed back to the API in order to fetch the next page. Hence, there is no way of knowing how many pages of results, you just have to wait until a response without a "nextToken" is received.

I would like to build something akin to a While() loop in other programming languages that works as follows:

nextTokenExists = FALSE

(fetch first page of results - got this done already)

check for nextToken

While (nextToken = TRUE):

    fetch next page of results using nextToken value

    merge these results to first page of results

    check for nextToken again and update value

Ultimately this loop should end when the "nextToken" is not found in the API response, and I would like to end up with a single query that is a merger of all of the results from within the loop.

I don't have a clue where to get started on this in Power Query, and I don't think the sample data is really relevant, but the API documentation in question for the data I am fetching can be found here: https://spytec.readme.io/reference/get-alerts 

Please let me know if more information is needed. Thanks in advance!