1  var baseFlatten = require('./_baseFlatten'),
 2      baseRest = require('./_baseRest'),
 3      baseUniq = require('./_baseUniq'),
 4      isArrayLikeObject = require('./isArrayLikeObject'),
 5      last = require('./last');
 6  
 7  /**
 8   * This method is like `_.union` except that it accepts `comparator` which
 9   * is invoked to compare elements of `arrays`. Result values are chosen from
10   * the first array in which the value occurs. The comparator is invoked
11   * with two arguments: (arrVal, othVal).
12   *
13   * @static
14   * @memberOf _
15   * @since 4.0.0
16   * @category Array
17   * @param {...Array} [arrays] The arrays to inspect.
18   * @param {Function} [comparator] The comparator invoked per element.
19   * @returns {Array} Returns the new array of combined values.
20   * @example
21   *
22   * var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
23   * var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];
24   *
25   * _.unionWith(objects, others, _.isEqual);
26   * // => [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 1 }]
27   */
28  var unionWith = baseRest(function(arrays) {
29    var comparator = last(arrays);
30    comparator = typeof comparator == 'function' ? comparator : undefined;
31    return baseUniq(baseFlatten(arrays, 1, isArrayLikeObject, true), undefined, comparator);
32  });
33  
34  module.exports = unionWith;