nl_tokens: The acknowledgement object
pl_tokens: function doFindAndDeleteUpdate ( datasetId , acknowledgement , callback ) { debug ( '[%s] doFindAndDeleteUpdate acknowledgement = %j' , datasetId , acknowledgement ) ; var updatesCollection = mongoClient . collection ( getDatasetUpdatesCollectionName ( datasetId ) ) ; updatesCollection . findOneAndDelete ( { cuid : acknowledgement . cuid , hash : acknowledgement . hash } , function ( err , result ) { if ( err ) { debugError ( '[%s] Failed to doFindAndDeleteUpdate due to error %s :: acknowledgement = %j' , datasetId , err , acknowledgement ) ; return callback ( err ) ; } return <mask> ( null , result . value ) ; } ) ; }