{"ast_node_type":"other","tokens":[{"end":82,"kind":"keyword","start":0,"text":"Err(err)"}]}
                    Err(err) if this.token == token::DotDotDot => return Err(err),
                    // If this is a C-variadic argument and we hit an error, return the error.
                    Err(err) if this.unmatched_angle_bracket_count > 0 => return Err(err),