{"ast_node_type":"other","tokens":[{"end":40,"kind":"keyword","start":0,"text":"///"}]}
/// the surrounding braces are stripped.
/// Parses a `TokenTree` that must be of the form `{ /* ... */ }`, and returns a `TokenStream` where
fn parse_token_tree<'a>(p: &mut Parser<'a>) -> PResult<'a, TokenStream> {