syntax_data: {"ast_node_type":"other","tokens":[{"end":82,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// triple, which stays the same even if the containing `SourceFile` has moved
context_before:     /// offsets into the `SourceMap`). Instead, we hash the (file name, line, column)
context_after:     /// within the `SourceMap`.