nl_tokens: Approximate gulp 4 . 0 series
pl_tokens: function series ( ) { const tasks = <mask> . prototype . slice . call ( arguments ) ; var fn = cb => cb ( ) ; if ( typeof tasks [ tasks . length - 1 ] === 'function' ) fn = tasks . pop ( ) ; return ( cb ) => { const tasks_with_cb = tasks . concat ( [ ( err ) => { if ( err ) return cb ( err ) ; fn ( cb ) ; } ] ) ; runSequence . apply ( this , tasks_with_cb ) ; } }