How to use the martinez-polygon-clipping.diff function in martinez-polygon-clipping

function difference(polygon1, polygon2) {
    var geom1 = getGeom(polygon1);
    var geom2 = getGeom(polygon2);
    var properties = polygon1.properties || {};

    // Issue #721 - JSTS/Martinez can't handle empty polygons
    geom1 = removeEmptyPolygon(geom1);
    geom2 = removeEmptyPolygon(geom2);
    if (!geom1) return null;
    if (!geom2) return feature(geom1, properties);

    var differenced = martinez.diff(geom1.coordinates, geom2.coordinates);
    if (differenced.length === 0) return null;
    if (differenced.length === 1) return polygon(differenced[0], properties);
    else return multiPolygon(differenced, properties);
}

Offset.prototype.padding = function(dist) {
  this.distance(dist);

  if (this._distance === 0) return this.ensureLastPoint(this.vertices);
  if (this.vertices.length === 2 && typeof this.vertices[0] === 'number') {
    return this.vertices;
  }

  var union = this.offsetLines(this._distance);
  var diff = martinez.diff(this.vertices, union);
  return orientRings(diff);
};

Offset.prototype.padding = function(dist) {
  this.distance(dist);

  if (this._distance === 0) return this.ensureLastPoint(this.vertices);
  if (this.vertices.length === 2 && typeof this.vertices[0] === 'number') {
    return this.vertices;
  }

  var union = this.offsetLines(this._distance);
  var diff = martinez.diff(this.vertices, union);
  return orientRings(diff);
};