syntax_data: {"ast_node_type":"other","tokens":[{"end":54,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:         // AppendOnlyVec, so we resort to this scheme.
context_before:         // This is equivalent to `.iter().copied().enumerate()`, but that isn't possible for
context_after:         self.proc_macro_quoted_spans.iter_enumerated()