text: export default function sorensen(a, b) {
    var ii = a.length;
    var up = 0;
    var down = 0;
    for (var i = 0; i < ii; i++) {
      up += Math.abs(a[i] - b[i]);
      down += a[i] + b[i];
    }
    return up / down;
  }
  