code: public void setDelta(double delta)
      {
          if(delta <= 0 || delta >= 1 || Double.isNaN(delta))
              throw new IllegalArgumentException("delta must be in (0,1), not " + delta);
          this.delta = delta;
      }
docs: Sets the upper bound on the false positive rate for detecting concept
  drifts
  @param delta the upper bound on false positives in (0,1)