code: function GeometryCollection(input){
      if(input && input.type === "GeometryCollection" && input.geometries){
        extend(this, input);
      } else if(isArray(input)) {
        this.geometries = input;
      } else if(input.coordinates && input.type){
        this.type = "GeometryCollection";
        this.geometries = [input];
      } else {
        throw "Terraformer: invalid input for Terraformer.GeometryCollection";
      }
  
      this.type = "GeometryCollection";
    }
docs: /*
  GeoJSON GeometryCollection Class
  new GeometryCollection();
  new GeometryCollection([geometry, geometry1]);
  new GeometryCollection({
  type: "GeometryCollection",
  coordinates: [geometry, geometry1]
  });