syntax_data: {"ast_node_type":"other","tokens":[{"end":76,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// expr, then this will return the span of the `$ident` macro variable.
context_before:     /// If "self" is the span of the outer_ident, and "within" is the span of the `($ident,)`
context_after:     pub fn within_macro(self, within: Span, sm: &SourceMap) -> Option<Span> {