syntax_data: {"ast_node_type":"other","tokens":[{"end":93,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:         // Note that we *could* forward to `mirror_expr` for that, but we can consolidate the
context_before:         // `mirror_exprs` may also recurse deeply, so it needs protection from stack overflow.
context_after:         // overhead of stack growth by doing it outside the iteration.