var baseMerge = require('./_baseMerge'),
      createAssigner = require('./_createAssigner');
  
  /**
   * This method is like `_.merge` except that it accepts `customizer` which
   * is 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 invoked with six arguments:
   * (objValue, srcValue, key, object, source, stack).
   *
   * **Note:** This method mutates `object`.
   *
   * @static
   * @memberOf _
   * @since 4.0.0
   * @category Object
   * @param {Object} object The destination object.
   * @param {...Object} sources The source objects.
   * @param {Function} customizer The function to customize assigned values.
   * @returns {Object} Returns `object`.
   * @example
   *
   * function customizer(objValue, srcValue) {
   *   if (_.isArray(objValue)) {
   *     return objValue.concat(srcValue);
   *   }
   * }
   *
   * var object = { 'a': [1], 'b': [2] };
   * var other = { 'a': [3], 'b': [4] };
   *
   * _.mergeWith(object, other, customizer);
   * // => { 'a': [1, 3], 'b': [2, 4] }
   */
  var mergeWith = createAssigner(function(object, source, srcIndex, customizer) {
    baseMerge(object, source, srcIndex, customizer);
  });
  
  module.exports = mergeWith;