Returns a series containing the predecessor and an element for each input, except for the first one. The returned series is one key shorter (it does not contain a value for the first key). ## Parameters - `series` - The input series to be aggregated. ## Example let input = series [ 1 => 'a'; 2 => 'b'; 3 => 'c'] let res = input.Pairwise() res = series [2 => ('a', 'b'); 3 => ('b', 'c') ] [category:Windowing, chunking and grouping]

public Series<K, Tuple<V, V>> Pairwise()