syntax_data: {"ast_node_type":"other","tokens":[{"end":32,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:         // #bb_check: match (rv)
context_before:         // #bb_call: rv = call fut.poll() (or future_drop_poll(fut) for internal future drops)
context_after:         //  pending => return rv (yield)