{"ast_node_type":"other","tokens":[{"end":113,"kind":"keyword","start":0,"text":"rustc_lexer::TokenKind::Frontmatter"}]}
                rustc_lexer::TokenKind::Frontmatter { has_invalid_preceding_whitespace, invalid_infostring } => {
                }
                    self.validate_frontmatter(start, has_invalid_preceding_whitespace, invalid_infostring);