Function try_parse_block 

fn try_parse_block<'i, T, F>(
    context: &ParserContext<'_>,
    input: &mut Parser<'i>,
    start: SourcePosition,
    start_location: SourceLocation,
    parse: F,
) -> Option<T>
where
    F: FnOnce(&mut Parser<'i>) -> Result<T, ParseError>,