syntax_data: {"ast_node_type":"other","tokens":[{"end":80,"kind":"keyword","start":0,"text":"if"}]}
source_snippet:                 if accept_newlines || !prev_source.trim_start().contains('\n') {
context_before:                 let prev_source = &prev_source[just_after_pat_plus_ws..];
context_after:                     return Some(sp.with_lo(BytePos(sp.lo().0 - len as u32)));