@Override
    public List<TensorFunction<NAMETYPE>> arguments() { return List.of(arg1, arg2); }
Convenience for euclidean distance between vectors.
euclidean_distance(a, b, mydim) == sqrt(sum(pow(a-b, 2), mydim))
@author arnej
vespajlib/src/main/java/com/yahoo/tensor/functions/EuclideanDistance.java