code: function (renderables) {
                  if (!renderables) {
                      throw new ArgumentError(
                          Logger.logMessage(Logger.LEVEL_SEVERE, "WktExporter", "exportRenderables",
                              "missingRenderables"));
                  }
  
                  if (renderables.length == 0) {
                      return;
                  }
  
                  if (renderables.length > 1) {
                      var sb = WktType.SupportedGeometries.GEOMETRY_COLLECTION + '(';
  
                      for (var i = 0; i < renderables.length; i++) {
                          var exportedRenderable = this.exportRenderable(renderables[i]);
  
                          if (exportedRenderable) {
                              sb = sb + exportedRenderable;
                              sb = sb + ',';
                          }
                      }
                      sb = sb.substring(0, sb.length - 1);
                      sb = sb + ')';
  
                      return sb;
                  }
                  else {
                      return this.exportRenderable(renderables[0]);
                  }
              }
docs: Exports a list of [Renderable]{@link Renderable} in WKT format of type GeometryCollection.
  @param {Renderable[]} renderables The renderables to export.
  @throws {ArgumentError} If the specified renderable is null or undefined.
  @returns {String} WKT format.