{"ast_node_type":"other","tokens":[{"end":61,"kind":"keyword","start":0,"text":".map_while(Either::<ast::TokenTree,"}]}
        .map_while(Either::<ast::TokenTree, ast::Meta>::cast)
    let spec_tt = ancestors_at_offset(&speculative_file, fake_ident_token.text_range().start())
        .last()?;