HandlerbarHelper.cs

public class HandlebarHelper
    {
        public static void  RegisterHelper()
        {
            RegisterArrayContainsHelper();
        }

        /// <summary>
        /// {{#arrayContains List<> limit}}
        ///     ... if condition true
        /// {{else}}
        ///    ... if condition false
        /// {{/arrayContains}}
        /// </summary>
        private static void RegisterArrayContainsHelper()
        {
            Handlebars.RegisterHelper("arrayContains", (writer, helper, context, parameters) =>
            {
                if (parameters.Count() < 2)
                {
                    writer.Write("arrayContains:Wrong number of arguments");
                    return;
                }

                var array = parameters[0] as IList;
                var number = Convert.ToInt32(parameters[1]);
                if (array.Count == number)
                {
                    helper.Template(writer, context);
                }
                else
                {
                    helper.Inverse(writer, context);
                }
            });
        }
    }