nl_tokens: Enumerate until index and return the element at index or consumes and return undefined
pl_tokens: function elementAtOrDefault ( index , or ) { return async function ( it ) { var e_19 , _a ; let i = 0 ; try { for ( var it_2 = __asyncValues ( it ) , it_2_1 ; it_2_1 = await it_2 . next ( ) , ! it_2_1 . done ; ) { const item = it_2_1 . value ; if ( i === index ) { return item ; } i = i + 1 ; } } catch ( e_19_1 ) { e_19 = { error : e_19_1 } ; } finally { <mask> { if ( it_2_1 && ! it_2_1 . done && ( _a = it_2 . return ) ) await _a . call ( it_2 ) ; } finally { if ( e_19 ) throw e_19 . error ; } } return or ; } ; }