nl_tokens: helper method to extract features for this chunk
pl_tokens: function extractFeatures ( chunk ) { //make it a F32A for efficiency var frame = arrayToTyped ( chunk ) ; //run the extraction of selected features var fset = Meyda . extract ( featuresToExtract , frame ) ; for ( let j = 0 ; j < featuresToExtract . <mask> ; j ++ ) { var feature = fset [ featuresToExtract [ j ] ] ; features [ featuresToExtract [ j ] ] . push ( feature ) ; } }