src/Application/Config.php
public function get(string $key, $default = null)
    {
        $result = $this->lookup($key);
        return $result === null ? $default : $this->fetchConstants($result);
    }
public function get(string $key, $default = null)
    {
        $result = $this->lookup($key);
        return $result === null ? $default : $this->fetchConstants($result);
    }
Gets value behind the key, or returns $default value if path does not exists.

@param string $key
@param null $default
@return null|string|string[]