syntax_data: {"ast_node_type":"other","tokens":[{"end":70,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:         // Use the global `SourceMap` to print the span. If that's not
context_before:     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
context_after:         // available, fall back to printing the raw values.