Cache.php
public function set($key, $value, $ttl = null)
    {
        $ttl = (null !== $ttl) ? $ttl : $this->ttl;

        if ($this->isSafe() && !empty($key)) {
            return $this->client->set($key, $value, $ttl);
        }

        return false;
    }
public function set($key, $value, $ttl = null)
    {
        $ttl = (null !== $ttl) ? $ttl : $this->ttl;

        if ($this->isSafe() && !empty($key)) {
            return $this->client->set($key, $value, $ttl);
        }

        return false;
    }
Add a key/value to the cache

@param string $key A unique key to identify the data you want to store
@param string $value The value you want to store in the cache
@param int $ttl Optional: Lifetime of the data
@access public
@return mixed Whatever the CacheClientObject returns, or false.