anchor.diff:      /// that starts at the first's start, and ends at the second's end.
       [<CompiledName("ConcatSpans")>]
       let concatSpans span1 span2 =
  -        if span1.IndexTo + 1UL = span2.IndexFrom then
  +        if span1.IndexTo + 1UL = span2.StartingPosition.Index then
               {span1 with IndexTo = span2.IndexTo}
           else
               failwithf "Trying to concatenate character span %O with %O." span1 span2
  
positive.code:     static member private Create(src) = {
          Source = src
          StartingIndex = 0UL
          CurrentLine = Position.Initial.Line
          CurrentColumn = Position.Initial.Column
          CurrentIndex = Position.Initial.Index
          _LastUnpinnedSpanPosition = Position.Initial
      }
      /// Creates a `CharStream` from a `ReadOnlyMemory` of characters.
  
negative.code:     /// Creates a `CharSpan` that contains the next `idxTo` characters of a `CharStream` from its position.
      /// On the dynamic block character stream, it ensures that the characters in the span stay in memory.
      [<CompiledName("PinSpan")>]
      let pinSpan (cs: CharStream) ({CharStreamIndex.Index = idxTo}) = {
          StartingPosition = cs.CurrentPosition
          IndexTo = idxTo
      }
  
  