/**
  * @param QOM\OrInterface $constraint
  *
  * @return string
  */
 public function walkOrConstraint(QOM\OrInterface $constraint)
 {
     return "(" . $this->walkConstraint($constraint->getConstraint1()) . " OR " . $this->walkConstraint($constraint->getConstraint2()) . ")";
 }
 private function walkOrConstraint(QOM\OrInterface $constraint)
 {
     $left = $this->walkConstraint($constraint->getConstraint1());
     $right = $this->walkConstraint($constraint->getConstraint2());
     return sprintf('(%s OR %s)', $left, $right);
 }