code: function toXY(coordinates, nesting) {
    if (nesting === 0) {
      return /** @type {Array<T>} */(coordinatesToXY0(/** @type {Coordinate} */(coordinates)));
    } else {
      for (let i = 0, ii = coordinates.length; i < ii; i++) {
        // @ts-ignore: TypeScript is not able to do recurtion with deferent type in generic
        coordinates[i] = toXY(coordinates[i], nesting - 1);
      }
    }
    return coordinates;
  }
docs: Convert a given coordinate or list of coordinates of any 'nesting' level
  to XY, i.e. remove any extra dimensions to the coordinates and keep only 2.
  
  @template {number|Coordinate|Array<Coordinate>|Array<Array<Coordinate>>} T
  @param {Array<T>} coordinates Coordinates
  @param {number} nesting Nesting level.
  @return {Array<T>} Converted coordinates.
  @private
  @hidden