anchor.diff:              // skip validation as incoming DNA should already be validated
               ok (Stitchable(Dna(stitchedSeq, false)))
   
  -    req |> (checkSeqs >> bind tryStitch)
  +    req |> (checkSeqs >=> tryStitch)
   
   type LoopoutSearchParams =
      {prefixSearchLength: int;
  
positive.code:         let errs = checkSeq req.seq0 req.margin0 0
          errs.AddRange(checkSeq req.seq1 req.margin1 1)
          if errs.Count <> 0 then
              fail(errs)
          else
              ok(req)
  
  
negative.code: /// The returned sequence will read in the sense direction of seq0.
  /// Any margin tails (for example, linkers) must be explicitly provided or stitching will fail.
  /// This function will check for exact overlap within the provided window.
  let overlapStitchWithMargins req : Result<OverlapStitchResult, string> =
      let minOverlap = int (defaultArg req.searchParams.minOverlap defaultMinOverlap)
          
      /// Check to make sure that:
  