src/AbstractCache.php
protected function keyToId($key): string
    {
        $this->assertKey($key);

        return sprintf('%s%s', $this->prefix, $key);
    }
protected function keyToId($key): string
    {
        $this->assertKey($key);

        return sprintf('%s%s', $this->prefix, $key);
    }
protected function keyToId ( $ key ) : string { $ this -> assertKey ( $ key ) ; return sprintf ( '%s%s' , $ this -> prefix , $ key ) ; }
Turn the key into a cache identifier

@param string $key
@return string
@throws InvalidArgumentException
Turn the key into a cache identifier