anchor.diff:  
     /// Function for filtering a single suggestion/option, defaults to
     /// [filterOption] method.
  -  StringSuggestionFilter _suggestionFilter;
  +  StringSuggestionFilter<T> _suggestionFilter;
   
     /// The [ItemRenderer] that sanitizes options and queries before filtering.
     ItemRenderer _sanitizeString;
  
positive.code: 
    StringSelectionOptions.withOptionGroups(List<OptionGroup<T>> optionGroups,
        {ItemRenderer<T> toFilterableString,
        StringSuggestionFilter suggestionFilter,
        ItemRenderer sanitizeString: _stringFormatSuggestion,
        bool shouldSort: false})
        : _toFilterableString = toFilterableString ??
  
negative.code: String _stringFormatSuggestion<T>(T value) =>
      '$value'.replaceAll(' ', '').toLowerCase();
  
  typedef bool StringSuggestionFilter<T>(T suggestion, String filterQuery);
  
  /// The class is meant to be used in areas where a selection can be represented
  /// as a string.
  