function baseSet(object, path, value, customizer) {
      if (!isObject(object)) {
        return object;
      }
      path = castPath(path, object);

      var index = -1,
          length = path.length,
          lastIndex = length - 1,
          nested = object;

      while (nested != null && ++index < length) {
        var key = toKey(path[index]),
            newValue = value;

        if (index != lastIndex) {
          var objValue = nested[key];
          newValue = customizer ? customizer(objValue, key, nested) : undefined;
          if (newValue === undefined) {
            newValue = isObject(objValue)
              ? objValue
              : (isIndex(path[index + 1]) ? [] : {});
          }
        }
        assignValue(nested, key, newValue);
        nested = nested[key];
      }
      return object;
    }
The base implementation of `_.set`.

@private
@param {Object} object The object to modify.
@param {Array|string} path The path of the property to set.
@param {*} value The value to set.
@param {Function} [customizer] The function to customize path creation.
@returns {Object} Returns `object`.