Ergo\Http\RequestFactory::_getSchemeHeader PHP Method

    private function _getSchemeHeader()
    {
        if (isset($this->_schemaHeader)) {
            $header = strtr(sprintf('HTTP_%s', strtoupper($this->_schemaHeader)), '-', '_');
            return isset($this->_server[$header]) ? $this->_server[$header] : null;
        }
    }