code: function baseInverter(object, setter, iteratee, accumulator) {
        baseForOwn(object, function(value, key, object) {
          setter(accumulator, iteratee(value), key, object);
        });
        return accumulator;
      }
docs: The base implementation of `_.invert` and `_.invertBy` which inverts
  `object` with values transformed by `iteratee` and set by `setter`.
  
  @private
  @param {Object} object The object to iterate over.
  @param {Function} setter The function to set `accumulator` values.
  @param {Function} iteratee The iteratee to transform values.
  @param {Object} accumulator The initial inverted object.
  @returns {Function} Returns `accumulator`.