anchor.diff:          /// <param name="source">The input sequence.</param>
           /// <returns>The found index or <c>None</c>.</returns>
           /// <exception cref="System.ArgumentNullException">Thrown when the input sequence is null.</exception>
  +        /// <remarks>This function consumes the whole input sequence before returning the result.</remarks>
           [<CompiledName("TryFindIndexBack")>]
           val tryFindIndexBack : predicate:('T -> bool) -> source:seq<'T> -> int option
   
  
positive.code:         /// <exception cref="System.Collections.Generic.KeyNotFoundException">Thrown if no element returns true when
          /// evaluated by the predicate</exception>
          /// <exception cref="System.ArgumentNullException">Thrown when the input sequence is null</exception>
          [<CompiledName("FindIndexBack")>]
          val findIndexBack: predicate:('T -> bool) -> source:seq<'T> -> int
  
  
negative.code:         /// <param name="state">The initial state.</param>
          /// <returns>The state object after the folding function is applied to each element of the sequence.</returns>
          /// <exception cref="System.ArgumentNullException">Thrown when the input sequence is null.</exception>
          /// <remarks>This function consumes the whole input sequence before returning the result.</remarks>
          [<CompiledName("FoldBack")>]
          val foldBack<'T,'State> : folder:('T -> 'State -> 'State) -> source:seq<'T> -> state:'State -> 'State
  
  