src/Business/Keys.php
public function rename($key, $newkey)
    {
        if ($key === $newkey) {
            throw new Exception('ERR source and destination objects are the same');
        } elseif (!$this->storage->hasKey($key)) {
            throw new Exception('ERR no such key');
        }

        if ($this->storage->hasKey($newkey)) {
            $this->del($newkey);
        }

        $this->storage->rename($key, $newkey);

        return true;
    }
public function rename($key, $newkey)
    {
        if ($key === $newkey) {
            throw new Exception('ERR source and destination objects are the same');
        } elseif (!$this->storage->hasKey($key)) {
            throw new Exception('ERR no such key');
        }

        if ($this->storage->hasKey($newkey)) {
            $this->del($newkey);
        }

        $this->storage->rename($key, $newkey);

        return true;
    }
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