syntax_data: {"ast_node_type":"other","tokens":[{"end":92,"kind":"keyword","start":0,"text":"assert_eq!(sf.lines(),"}]}
source_snippet:     assert_eq!(sf.lines(), &[RelativeBytePos(0), RelativeBytePos(14), RelativeBytePos(25)]);
context_before:     sf.start_pos = BytePos(3);