public function readFrom($input)
    {
        if ($this->isFile($input)) {
            if (is_readable($input) === false) {
                throw new \RuntimeException(
                    sprintf('Unable to parse "%s" as the file is not readable.', $input)
                );
            }

            // $input is a filepath, so we load that file
            $input = file_get_contents($input);
        }

        return trim($input);
    }