appendCoordinates(coordinates) {
    const mode = this.mode_;
    const newDrawing = !this.sketchFeature_;
    if (newDrawing) {
      this.startDrawing_(coordinates[0]);
    }
    /** @type {LineCoordType} */
    let sketchCoords;
    if (mode === 'LineString' || mode === 'Circle') {
      sketchCoords = /** @type {LineCoordType} */ (this.sketchCoords_);
    } else if (mode === 'Polygon') {
      sketchCoords =
        this.sketchCoords_ && this.sketchCoords_.length
          ? /** @type {PolyCoordType} */ (this.sketchCoords_)[0]
          : [];
    } else {
      return;
    }

    if (newDrawing) {
      sketchCoords.shift();
    }

    // Remove last coordinate from sketch drawing (this coordinate follows cursor position)
    sketchCoords.pop();

    // Append coordinate list
    for (let i = 0; i < coordinates.length; i++) {
      this.addToDrawing_(coordinates[i]);
    }

    const ending = coordinates[coordinates.length - 1];
    // Duplicate last coordinate for sketch drawing (cursor position)
    this.sketchFeature_ = this.addToDrawing_(ending);
    this.modifyDrawing_(ending);
  }
Append coordinates to the end of the geometry that is currently being drawn.
This can be used when drawing LineStrings or Polygons. Coordinates will
either be appended to the current LineString or the outer ring of the current
Polygon. If no geometry is being drawn, a new one will be created.
@param {!LineCoordType} coordinates Linear coordinates to be appended to
the coordinate array.
@api