/// <summary>
 /// Sets the Warning header of the request to the specified code, agent, text, and date.
 /// </summary>
 /// <param name="code">The Warning header code.</param>
 /// <param name="agent">The Warning header agent.</param>
 /// <param name="text">The Warning header text.</param>
 /// <param name="date">The Warning header date.</param>
 /// <returns>An <see cref="IRequest"/> object that represents the request.</returns>
 public static IRequest Warning(this IWith @this, int code, string agent, string text, DateTimeOffset date)
 => @this.Warning(new WarningHeaderValue(code, agent, text, date));
 /// <summary>
 /// Sets the Warning header of the request to the specified code, agent, and text.
 /// </summary>
 /// <param name="code">The Warning header code.</param>
 /// <param name="agent">The Warning header agent.</param>
 /// <param name="text">The Warning header text.</param>
 /// <returns>An <see cref="IRequest"/> object that represents the request.</returns>
 public static IRequest Warning(this IWith @this, int code, string agent, string text)
 => @this.Warning(new WarningHeaderValue(code, agent, text));