code: function boundPoints (points) {
    var bounds = new Array(points.length)
    for (var i = 0; i < points.length; ++i) {
      var p = points[i]
      bounds[i] = [
        nextafter(p[0], -Infinity),
        nextafter(p[1], -Infinity),
        nextafter(p[0], Infinity),
        nextafter(p[1], Infinity)
      ]
    }
    return bounds
  }
docs: Convert a list of points into bounding boxes by duplicating coords