anchor.diff:    static const _secondCode = 0x73; /*s*/
     static const _fractionSecondCode = 0x53; /*S*/
   
  -  /// The format pattern string of this formatter
  +  /// The format pattern string of this formatter.
     final String pattern;
   
     /// Whether to create UTC [DateTime] objects when parsing.
  
positive.code: /// `YYYY------MM`. When encoding a [DateTime], the non-format characters are in
  /// the output verbatim.
  ///
  /// Note: this class differs from [DateFormat] in that here, the characters are
  /// treated literally, i.e., the format string `YYY` matching `996` would result
  /// in the same as calling `DateTime(996)`.
  class FixedDateTimeFormatter {
    static const _powersOfTen = [1, 10, 100, 1000, 10000, 100000];
    static const _validFormatCharacters = [
  
negative.code: 
    /// Converts a [DateTime] to a [String] as specified by the [pattern].
    ///
    /// The [dateTime.year] must not be negative.
    String encode(DateTime dateTime) {
      if (dateTime.year < 0) {
        throw ArgumentError.value(
          dateTime,
          'dateTime',
          'Year must not be negative',
        );
      }
      var buffer = StringBuffer();
      for (var i = 0; i < _blocks.length; i++) {
  