/// <summary>
 /// Appends the specified <paramref name="format"/> to the existing content with information from the
 /// <paramref name="provider"/> after replacing each format item with the HTML encoded <see cref="string"/>
 /// representation of the corresponding item in the <paramref name="args"/> array.
 /// </summary>
 /// <param name="provider">An object that supplies culture-specific formatting information.</param>
 /// <param name="format">
 /// The composite format <see cref="string"/> (see http://msdn.microsoft.com/en-us/library/txafckwd.aspx).
 /// </param>
 /// <param name="args">The object array to format.</param>
 /// <returns>A reference to this instance after the append operation has completed.</returns>
 public TagHelperContent AppendFormat(IFormatProvider provider, string format, params object[] args)
 {
     HtmlContentBuilderExtensions.AppendFormat(this, provider, format, args);
     return(this);
 }
 /// <summary>
 /// Appends the specified <paramref name="format"/> to the existing content after
 /// replacing each format item with the HTML encoded <see cref="string"/> representation of the
 /// corresponding item in the <paramref name="args"/> array.
 /// </summary>
 /// <param name="format">
 /// The composite format <see cref="string"/> (see http://msdn.microsoft.com/en-us/library/txafckwd.aspx).
 /// </param>
 /// <param name="args">The object array to format.</param>
 /// <returns>A reference to this instance after the append operation has completed.</returns>
 public TagHelperContent AppendFormat(string format, params object[] args)
 {
     HtmlContentBuilderExtensions.AppendFormat(this, null, format, args);
     return(this);
 }