nl_tokens: Returns a promise of true if evaluating the iterable gives any items false otherwise
pl_tokens: async function empty ( source ) { var e_34 , _a ; let i = 0 ; <mask> { for ( var source_5 = __asyncValues ( source ) , source_5_1 ; source_5_1 = await source_5 . next ( ) , ! source_5_1 . done ; ) { const it = source_5_1 . value ; return false ; } } catch ( e_34_1 ) { e_34 = { error : e_34_1 } ; } finally { try { if ( source_5_1 && ! source_5_1 . done && ( _a = source_5 . return ) ) await _a . call ( source_5 ) ; } finally { if ( e_34 ) throw e_34 . error ; } } return true ; }