anchor.diff:    /// through earlier elements, for example when iterating a [List].
     /// Such iterables are allowed to ignore the initial skipped elements.
     ///
  +  /// Example:
  +  /// ```dart
  +  /// final numbers = <int>[1, 2, 3, 5, 6, 7];
  +  /// final result = numbers.skip(4); // (6, 7)
  +  /// final skipAll = numbers.skip(100); // () - no elements.
  +  /// ```
  +  ///
     /// The [count] must not be negative.
     Iterable<E> skip(int count) {
       return SkipIterable<E>(this, count);
  
positive.code:   ///
    /// Checks every element in iteration order, and returns `true` if
    /// any of them make [test] return `true`, otherwise returns false.
    bool any(bool test(E element)) {
      for (E element in this) {
        if (test(element)) return true;
  
negative.code:   /// ```
    /// Example of calculating the sum of an iterable:
    /// ```dart
    /// final numbers = <double>[10, 2, 5, 0.5];
    /// const initialValue = 100.0;
    /// final result = numbers.fold<double>(
    ///     initialValue, (previousValue, element) => previousValue + element);
    /// print(result); // 117.5
    /// ```
    T fold<T>(T initialValue, T combine(T previousValue, E element)) {
      var value = initialValue;
  