code: public function removeToken($tokenId): ?string
      {
          $this->assertInitialized();
  
          $token = null;
  
          if (isset($this->tokens[$tokenId])) {
              $token = $this->tokens[$tokenId];
              $this->tokens[$tokenId] = null;
          }
  
          $this->usedTokens[$tokenId] = true;
  
          return $token;
      }
docs: {@inheritdoc}