original_string: public function getNormalizedIdentifier($document)
      {
          if (is_scalar($document)) {
              throw new \InvalidArgumentException('Invalid argument, object or null required');
          }
  
          // the document is not managed
          if (!$document || !$this->getDocumentManager()->contains($document)) {
              return;
          }
  
          $values = $this->getIdentifierValues($document);
  
          return $values[0];
      }
code: public function getNormalizedIdentifier($document)
      {
          if (is_scalar($document)) {
              throw new \InvalidArgumentException('Invalid argument, object or null required');
          }
  
          // the document is not managed
          if (!$document || !$this->getDocumentManager()->contains($document)) {
              return;
          }
  
          $values = $this->getIdentifierValues($document);
  
          return $values[0];
      }
code_tokens: public function getNormalizedIdentifier ( $ document ) { if ( is_scalar ( $ document ) ) { throw new \ InvalidArgumentException ( 'Invalid argument, object or null required' ) ; } // the document is not managed if ( ! $ document || ! $ this -> getDocumentManager ( ) -> contains ( $ document ) ) { return ; } $ values = $ this -> getIdentifierValues ( $ document ) ; return $ values [ 0 ] ; }
docstring: This is just taking the id out of the array again.
  
  {@inheritdoc}
  
  @throws \InvalidArgumentException if $document is not an object or null
docstring_tokens: This is just taking the id out of the array again .