code: public function process(File $phpcsFile, $stackPtr)
      {
          $tokens = $phpcsFile->getTokens();
  
          $endOfStatement = $phpcsFile->findEndOfStatement($stackPtr);
          $implements = $phpcsFile->findNext(
              T_IMPLEMENTS,
              $stackPtr,
              $endOfStatement,
              false,
              null,
              true
          );
  
          if ($implements !== false) {
              // interface found
              $phpcsFile->recordMetric($stackPtr, 'Class ImplementExtend', 'yes');
              return;
          }
  
          $extends = $phpcsFile->findNext(
              T_EXTENDS,
              $stackPtr,
              $endOfStatement,
              false,
              null,
              true
          );
  
          if ($extends !== false) {
              // parent class found
              $phpcsFile->recordMetric($stackPtr, 'Class ImplementExtend', 'yes');
              return;
          }
  
          $error   = 'Class "%s" must implement an interface or extend another class';
          $nextVar = $tokens[$phpcsFile->findNext([T_STRING], $stackPtr)];
          $data    = [$nextVar['content']];
  
          $phpcsFile->addError($error, $stackPtr, 'NotAllowed', $data);
          $phpcsFile->recordMetric($stackPtr, 'Class implements', 'no');
      }
docs: {@inheritdoc}