syntax_data: {"ast_node_type":"other","tokens":[{"end":76,"kind":"keyword","start":0,"text":"///"}]}
source_snippet: ///   needed for `ctxt` values depend partly on the crate size and partly on
context_before: ///   `parent` is large, or if both values are non-zero. The number of bits
context_after: ///   the form of the code. No crates in `rustc-perf` need more than 15 bits