/// <summary>
 /// 格式化
 /// </summary>
 public string Format(string format, object arg, IFormatProvider formatProvider)
 {
     if (!(arg is ILogContent content))
     {
         return(string.Empty);
     }
     return(_format.Format(content));
 }
        /// <summary>
        /// 格式化
        /// </summary>
        /// <param name="format">包含格式规范的格式字符串。</param>
        /// <param name="arg">要设置格式的对象。</param>
        /// <param name="formatProvider">一个对象,它提供有关当前实例的格式信息。</param>
        /// <returns></returns>
        public string Format(string format, object arg, IFormatProvider formatProvider)
        {
            var content = arg as ILogContent;

            if (content == null)
            {
                return(string.Empty);
            }
            return(_format.Format(content));
        }