   ///   negative only if the collection conforms to the
   ///   `BidirectionalCollection` protocol.
   ///
-  /// - Complexity: O(1) if the collection conforms to
-  ///   `RandomAccessCollection`; otherwise, O(*k*), where *k* is the
-  ///   resulting distance.
+  /// - Complexity: O(1)
   func distance(from start: Index, to end: Index) -> Int
 }
 

  ///   index would be beyond `limit` in the direction of movement. In that
  ///   case, the method returns `nil`.
  ///
  /// - Complexity: O(1) if the collection conforms to
  ///   `RandomAccessCollection`; otherwise, O(*k*), where *k* is the absolute
  ///   value of `distance`.
  func index(
    _ i: Index, offsetBy distance: Int, limitedBy limit: Index
  ) -> Index?

  ///   is the same value as the result of `abs(distance)` calls to
  ///   `index(before:)`.
  ///
  /// - Complexity: O(1)
  func index(_ i: Index, offsetBy distance: Int) -> Index

  /// Returns an index that is the specified distance from the given index,
