syntax_data: {"ast_node_type":"other","tokens":[{"end":87,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:             // positions in the `SourceMap`, even in the presence of zero-length files.
context_before:             // Add one so there is some space between files. This lets us distinguish
context_after:             last_file.end_position().0.checked_add(1).ok_or(OffsetOverflowError)?