code: function update(object, path, updater) {
        return object == null ? object : baseUpdate(object, path, castFunction(updater));
      }
docs: This method is like `_.set` except that accepts `updater` to produce the
  value to set. Use `_.updateWith` to customize `path` creation. The `updater`
  is invoked with one argument: (value).
  
  **Note:** This method mutates `object`.
  
  @static
  @memberOf _
  @since 4.6.0
  @category Object
  @param {Object} object The object to modify.
  @param {Array|string} path The path of the property to set.
  @param {Function} updater The function to produce the updated value.
  @returns {Object} Returns `object`.
  @example
  
  var object = { 'a': [{ 'b': { 'c': 3 } }] };
  
  _.update(object, 'a[0].b.c', function(n) { return n * n; });
  console.log(object.a[0].b.c);
  // => 9
  
  _.update(object, 'x[0].y.z', function(n) { return n ? n + 1 : 0; });
  console.log(object.x[0].y.z);
  // => 0