protected function removeWorstPerformersFromPopulation()
 {
     $worstPerformerIdentifiers = $this->scoreManager->getWorstPerformersUniqueIdentifiers($this->citizensCountToReplacePerGeneration);
     foreach ($worstPerformerIdentifiers as $identifier) {
         $this->population->removeCitizenByUniqueIdentifier($identifier);
     }
 }
 public function testWorstPerformerUniqueIdentifier()
 {
     $worstPerformersIdentifiers = $this->scoreManager->getWorstPerformersUniqueIdentifiers(1);
     $this->assertEquals($this->lowestScoreCitizen->getUniqueIdentifier(), $worstPerformersIdentifiers[0]);
 }