syntax_data: {"ast_node_type":"other","tokens":[{"end":65,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// "none" implies a bare metal target without `std` library.
context_before:     /// OS name to use for conditional compilation (`target_os`). Defaults to "none".
context_after:     /// A couple of targets having `std` also use "unknown" as an `os` value,