old_contents: /**
   * Creates a {@link LineString} {@link Feature} based on a
   * coordinate array. Properties can be added optionally.
   *
   * @module turf/linestring
   * @category helper
   * @param {Array<Array<Number>>} coordinates an array of Positions
   * @param {Object=} properties an Object of key-value pairs to add as properties
   * @returns {LineString} a LineString feature
   * @throws {Error} if no coordinates are passed
   * @example
   * var linestring1 = turf.linestring([
   *	[-21.964416, 64.148203],
   *	[-21.956176, 64.141316],
   *	[-21.93901, 64.135924],
   *	[-21.927337, 64.136673]
   * ]);
   * var linestring2 = turf.linestring([
   *	[-21.929054, 64.127985],
   *	[-21.912918, 64.134726],
   *	[-21.916007, 64.141016],
   * 	[-21.930084, 64.14446]
   * ], {name: 'line 1', distance: 145});
   *
   * //=linestring1
   *
   * //=linestring2
   */
  module.exports = function(coordinates, properties){
    if (!coordinates) {
        throw new Error('No coordinates passed');
    }
    return {
      "type": "Feature",
      "geometry": {
        "type": "LineString",
        "coordinates": coordinates
      },
      "properties": properties || {}
    };
  };
  
new_contents: /**
   * Creates a {@link LineString} based on a
   * coordinate array. Properties can be added optionally.
   *
   * @module turf/linestring
   * @category helper
   * @param {Array<Array<Number>>} coordinates an array of Positions
   * @param {Object=} properties an Object of key-value pairs to add as properties
   * @returns {Feature<LineString>} a LineString feature
   * @throws {Error} if no coordinates are passed
   * @example
   * var linestring1 = turf.linestring([
   *	[-21.964416, 64.148203],
   *	[-21.956176, 64.141316],
   *	[-21.93901, 64.135924],
   *	[-21.927337, 64.136673]
   * ]);
   * var linestring2 = turf.linestring([
   *	[-21.929054, 64.127985],
   *	[-21.912918, 64.134726],
   *	[-21.916007, 64.141016],
   * 	[-21.930084, 64.14446]
   * ], {name: 'line 1', distance: 145});
   *
   * //=linestring1
   *
   * //=linestring2
   */
  module.exports = function(coordinates, properties){
    if (!coordinates) {
        throw new Error('No coordinates passed');
    }
    return {
      "type": "Feature",
      "geometry": {
        "type": "LineString",
        "coordinates": coordinates
      },
      "properties": properties || {}
    };
  };
  
subject: Switch doc to closure compiler templating