function _largest(x, y) {
    try {
      return larger(x, y) ? x : y;
    } catch (err) {
      throw improveErrorMessage(err, 'max', y);
    }
  }
Return the largest of two values
@param {*} x
@param {*} y
@returns {*} Returns x when x is largest, or y when y is largest
@private