define(['../internal/baseMerge', '../internal/createAssigner'], function(baseMerge, createAssigner) {

  /**
   * Recursively merges own enumerable properties of the source object(s), that
   * don't resolve to `undefined` into the destination object. Subsequent sources
   * overwrite property assignments of previous sources. If `customizer` is
   * provided it's invoked to produce the merged values of the destination and
   * source properties. If `customizer` returns `undefined` merging is handled
   * by the method instead. The `customizer` is bound to `thisArg` and invoked
   * with five arguments: (objectValue, sourceValue, key, object, source).
   *
   * @static
   * @memberOf _
   * @category Object
   * @param {Object} object The destination object.
   * @param {...Object} [sources] The source objects.
   * @param {Function} [customizer] The function to customize assigned values.
   * @param {*} [thisArg] The `this` binding of `customizer`.
   * @returns {Object} Returns `object`.
   * @example
   *
   * var users = {
   *   'data': [{ 'user': 'barney' }, { 'user': 'fred' }]
   * };
   *
   * var ages = {
   *   'data': [{ 'age': 36 }, { 'age': 40 }]
   * };
   *
   * _.merge(users, ages);
   * // => { 'data': [{ 'user': 'barney', 'age': 36 }, { 'user': 'fred', 'age': 40 }] }
   *
   * // using a customizer callback
   * var object = {
   *   'fruits': ['apple'],
   *   'vegetables': ['beet']
   * };
   *
   * var other = {
   *   'fruits': ['banana'],
   *   'vegetables': ['carrot']
   * };
   *
   * _.merge(object, other, function(a, b) {
   *   if (_.isArray(a)) {
   *     return a.concat(b);
   *   }
   * });
   * // => { 'fruits': ['apple', 'banana'], 'vegetables': ['beet', 'carrot'] }
   */
  var merge = createAssigner(baseMerge);

  return merge;
});