syntax_data: {"ast_node_type":"other","tokens":[{"end":63,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:         // `outer_exclusive_binder` is always 1 higher than the
context_before:         // bound at `outer_index` or above (because
context_after:         // content in `t`). Therefore, `t` has some escaping vars.