public function createReferencePoint($inputSize, $keyname = null)
    {
        if ($keyname === null) {
            $keyname = 'Step: '.(count($this->referencePoints) + 1);
        }

        if (!array_key_exists($keyname, $this->referencePoints)) {
            $this->referencePoints[$keyname] = new ReferencePoint($keyname, $inputSize);
        } else {
            $this->referencePoints[$keyname]->addBytes($inputSize);
        }

        return $this->referencePoints;
    }