syntax_data: {"ast_node_type":"other","tokens":[{"end":82,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:             // If this eats a by-ref default binding mode, label the binding mode.
context_before:         if let Some((default_mode_span, default_ref_mutbl)) = self.default_mode_span {
context_after:             self.default_mode_labels.insert(default_mode_span, default_ref_mutbl);