function assert_class_string(object, class_string, description) {
        var actual = {}.toString.call(object);
        var expected = "[object " + class_string + "]";
        assert(same_value(actual, expected), "assert_class_string", description,
                                             "expected ${expected} but got ${actual}",
                                             {expected:expected, actual:actual});
    }
Assert that the class string of ``object`` as returned in
``Object.prototype.toString`` is equal to ``class_name``.

@param {Object} object - Object to stringify.
@param {string} class_string - Expected class string for ``object``.
@param {string} [description] - Description of the condition being tested.