syntax_data: {"ast_node_type":"other","tokens":[{"end":81,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// number. If the source_file is empty or the position is located before the
context_before:     /// index into the `lines` array of this `SourceFile`, not the 1-based line
context_after:     /// first line, `None` is returned.