anchor.diff:    ///
     /// If [mode] is provided as either [HtmlEscapeMode.attribute] or
     /// [HtmlEscapeMode.element], only the corresponding subset of HTML
  -  /// characters are escaped.
  +  /// characters is escaped.
     /// The default is to escape all HTML characters.
     const HtmlEscape([this.mode = HtmlEscapeMode.unknown]);
   
  
positive.code: 
  /// HTML escape modes.
  ///
  /// Allows specifying a mode for HTML escaping that depend on the context
  /// where the escaped result is going to be used.
  /// The relevant contexts are:
  ///
  
negative.code: ///
  /// Custom escape modes can be created using the [HtmlEscapeMode.HtmlEscapeMode]
  /// constructor.
  ///
  /// Example:
  /// ```dart
  /// const htmlEscapeMode = HtmlEscapeMode(
  ///   name: 'custom',
  ///   escapeLtGt: true,
  ///   escapeQuot: false,
  ///   escapeApos: false,
  ///   escapeSlash: false,
  ///  );
  ///
  /// const HtmlEscape htmlEscape = HtmlEscape(htmlEscapeMode);
  /// String unescaped = 'Text & subject';
  /// String escaped = htmlEscape.convert(unescaped);
  /// print(escaped); // Text &amp; subject
  ///
  /// unescaped = '10 > 1 and 1 < 10';
  /// escaped = htmlEscape.convert(unescaped);
  /// print(escaped); // 10 &gt; 1 and 1 &lt; 10
  ///
  /// unescaped = "Single-quoted: 'text'";
  /// escaped = htmlEscape.convert(unescaped);
  /// print(escaped); // Single-quoted: 'text'
  ///
  /// unescaped = 'Double-quoted: "text"';
  /// escaped = htmlEscape.convert(unescaped);
  /// print(escaped); // Double-quoted: "text"
  ///
  /// unescaped = 'Path: /system/';
  /// escaped = htmlEscape.convert(unescaped);
  /// print(escaped); // Path: /system/
  /// ```
  class HtmlEscapeMode {
    final String _name;
  
  