Comprehension
Generated from the engine's own definition: compute-engine's symbol, which we neither extend nor document by hand. No examples yet — the crosswalk is the reason it has a page.
Value-producing comprehension: evaluate `body` in nested iteration over one or more `Element` clauses and collect the results into an indexed collection (a `List`). Later clauses see earlier bindings; independent clauses produce a Cartesian product.
Comprehension(body: expression, iterators: expression+) -> indexed_collectionas compute-engine declares it