syntax_data: {"ast_node_type":"other","tokens":[{"end":86,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:             // function in case this is a special coroutine backing an async construct
context_before:             // have an ordinary coroutine, the `Future::poll(...) -> Poll`
context_after:             // or the `Iterator::next(...) -> Option` function in case this is a