/// <summary>
    ///   <para>Initializes HTML helper object for rendering of 2GIS widgets.</para>
    /// </summary>
    /// <param name="html">Helper object to call method on.</param>
    /// <returns>Widgets factory helper.</returns>
    /// <exception cref="ArgumentNullException">If <paramref name="html"/> is a <c>null</c> reference.</exception>
    public static IDoubleGisHtmlHelper DoubleGis(this HtmlHelper html)
    {
      Assertion.NotNull(html);

      return doublegis ?? (doublegis = new DoubleGisHtmlHelper());
    }
        /// <summary>
        ///   <para>Initializes HTML helper object for rendering of 2GIS widgets.</para>
        /// </summary>
        /// <param name="html">Helper object to call method on.</param>
        /// <returns>Widgets factory helper.</returns>
        /// <exception cref="ArgumentNullException">If <paramref name="html"/> is a <c>null</c> reference.</exception>
        public static IDoubleGisHtmlHelper DoubleGis(this HtmlHelper html)
        {
            Assertion.NotNull(html);

            return(doublegis ?? (doublegis = new DoubleGisHtmlHelper()));
        }