/// <summary>
        /// Asserts that the element is enabled.
        /// </summary>
        /// <param name="handle">An <see cref="ElementHandle"/></param>
        /// <param name="message">Optional failure message</param>
        /// <remarks><![CDATA[Elements: <button>, <command>, <fieldset>, <input>, <keygen>, <optgroup>, <option>, <select>, <textarea>]]></remarks>
        /// <returns>The <see cref="ElementHandle"/> for method chaining</returns>
        public static ElementHandle ShouldBeEnabled(this ElementHandle handle, string message = null)
        {
            if (handle.IsDisabled())
            {
                Throw.ShouldBeEnabled(handle, message);
            }

            return(handle);
        }