syntax_data: {"ast_node_type":"other","tokens":[{"end":73,"kind":"keyword","start":0,"text":"///"}]}
source_snippet: ///   `SpanData`, which means intering will happen if `ctxt` is large, if
context_before: /// - `ctxt_or_parent_or_marker` is 16 bits in `Span` and two 32 bit fields in
context_after: ///   `parent` is large, or if both values are non-zero. The number of bits