public function loadCallback(string $value = null)
    {
        return null === $value ? null : trim(\base64_encode($value), '=');
    }
public function loadCallback(string $value = null)
    {
        return null === $value ? null : trim(\base64_encode($value), '=');
    }
public function loadCallback ( string $ value = null ) { return null === $ value ? null : trim ( \ base64_encode ( $ value ) , '=' ) ; }
Base64 encode.

@param string|null $value The value.

@return string|null
Base64 encode .