Modified Variables Propagation in GET Request Nested Loop

This workflow demostrates the use of the option "Propagate modified loop variables" available in Loop End nodes.
Given a list of search terms, the workflow iterates over each search item to avoid overloading (outer loop) and then it sends GET request to the Google Books API for each search term to get the relevant book authors and titles. The maximum results in Google Books API is 40, therefore, for each search term, the workflow repeats sending GET requests untill the starting index of an item (a book) is larger than the total number of available items for this search term (inner loop).

The workflow demonstrates the difference for external, injected, and internal variables as well as the difference between the propagation option on (in the inner loop) and off (in the outer loop).