anchor.diff:      array:set(Bucket, array:get(Bucket, Array) + 1, Array).
   
   check_histogram(W, Rounds, StdDevs, Histogram, Buckets) ->
  -    %%PrevBucket = 512,
  -    %%Bucket = PrevBucket - 1,
  -    %%P = 0.5 * math:erfc(PrevBucket / W),
       TargetP = 0.5 * math:erfc(Buckets / W),
       P = 0.0,
       N = 0,
  
positive.code:     P = 0.5 * math:erfc(Bucket / W),
      BucketP = P - PrevP,
      if
          TargetP =< BucketP ->
              check_histogram(
                W, Rounds, StdDevs, Histogram, TargetP,
                Bucket - 1, PrevBucket, PrevP, N);
  
negative.code:             UpperLimit = ceil(Exp + Threshold),
              if
                  N < LowerLimit; UpperLimit < N ->
                      [#{bucket => {Bucket, PrevBucket}, n => N,
                         lower => LowerLimit, upper => UpperLimit} |
                       check_histogram(
                         W, Rounds, StdDevs, Histogram, TargetP,
  