fn try_pop_both<'s>(
entered: &Stack<EnteredDelimiter<'s>>
) -> Option<(&'s Syntax<'s>, &'s Syntax<'s>, Stack<EnteredDelimiter<'s>>)>
fn try_pop_both<'s>(
entered: &Stack<EnteredDelimiter<'s>>
) -> Option<(&'s Syntax<'s>, &'s Syntax<'s>, Stack<EnteredDelimiter<'s>>)>