code: function addFaces(faces, className, numJitters = 0) {
        if (!faces || !faces.length) {
          throw new Error('train - expected an array containing atleast one face image')
        }
  
        if (!className) {
          throw new Error('train - expected a class name')
        }
  
        const faceDescriptors = flatten(
          faces.map(f => getJitteredFaces(f, numJitters).map(jf => getNet().computeFaceDescriptor(jf)))
        )
  
        addFaceDescriptors(faceDescriptors, className)
      }
docs: /* compute the face descriptors for all faces of the given class, which are used for prediction /* this function is used to "train" the recognizer and has to be performed for all persons faces, /* which you want to recognize before running prediction