syntax_data: {"ast_node_type":"other","tokens":[{"end":57,"kind":"keyword","start":0,"text":"for"}]}
source_snippet:         for (expn_id, transparency) in self.marks(ctxt) {
context_before:         // See the example at `test/ui/hygiene/legacy_interaction.rs`.
context_after:             call_site_ctxt = self.alloc_ctxt(call_site_ctxt, expn_id, transparency);