anchor.diff:  /// An error which is thrown when an object cannot be encoded.
   ///
   /// Example:
  +///
   ///     var encoder = new TomlEncoder();
   ///     encoder.encode({'a': null});
  +///
   /// throws an [UnknownValueTypeError] because `null` is not a valid TOML value.
   class UnknownValueTypeError {
   
  
positive.code: /// sequence.
  ///
  /// Example:
  ///     dir = "some\windows\path"
  /// throws an [InvalidEscapeSequenceError] with `[escapeSequence] = r'\w'`.
  class InvalidEscapeSequenceError {
  
  
negative.code: /// a table.
  ///
  /// Example:
  ///
  ///     [a]
  ///     b = 1
  ///
  ///     [a.b.c]
  ///     d = 2
  ///
  /// throws a [NotATableError] because `a.b.c` fails to create a sub-table of
  /// `a.b` which is an integer rather than not a table.
  class NotATableError {
  