readRegion(source) {
    const regions = [];
    if (typeof source === 'string') {
      const doc = parse(source);
      extend(regions, this.readRegionFromDocument(doc));
    } else if (isDocument(source)) {
      extend(
        regions,
        this.readRegionFromDocument(/** @type {Document} */ (source)),
      );
    } else {
      extend(regions, this.readRegionFromNode(/** @type {Element} */ (source)));
    }
    return regions;
  }
Read the regions of the KML.

@param {Document|Element|string} source Source.
@return {Array<Object>} Regions.
@api