nl_tokens: Prepend an item to the beginning of an iterable
pl_tokens: function unshift ( ... next ) { return function ( it ) { return __asyncGenerator ( this , arguments , function * ( ) { for ( let i = 0 ; i < next . length ; ++ i ) yield yield __await ( <mask> [ next . length - i - 1 ] ) ; yield __await ( yield * __asyncDelegator ( __asyncValues ( it ) ) ) ; } ) ; } ; }