syntax_data: {"ast_node_type":"variable","tokens":[{"end":47,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let hi = self.lookup_char_pos(sp.hi());
context_before:         let lo = self.lookup_char_pos(sp.lo());
context_after:         (Some(lo.file), lo.line, lo.col.to_usize() + 1, hi.line, hi.col.to_usize() + 1)