/**
  * Get trace variable instance to save.
  * 
  * @param string $identifier
  * @param string $value
  * @return \taoResultServer_models_classes_TraceVariable variable instance to save.
  */
 private function getVariable($identifier, $value)
 {
     $metaVariable = new \taoResultServer_models_classes_TraceVariable();
     $metaVariable->setIdentifier($identifier);
     $metaVariable->setBaseType('string');
     $metaVariable->setCardinality(Cardinality::getNameByConstant(Cardinality::SINGLE));
     $metaVariable->setTrace($value);
     return $metaVariable;
 }