public function input($filename, $input)
    {
        if (substr($filename, strlen($this->_settings['ext']) * -1) !== $this->_settings['ext']) {
            return $input;
        }
        $cmd = $this->_settings['node'] . ' ' . $this->_settings['coffee'] . ' -c -p -s ';
        $env = array('NODE_PATH' => $this->_settings['node_path']);
        return $this->_runCmd($cmd, $input, $env);
    }