core-bundle/src/Csrf/MemoryTokenStorage.php
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 $token;
    }
public function removeToken($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;
    }
{@inheritdoc}