Update Session Headers: update a HTTP Session Headers

        ``alias`` Robot Framework alias to identify the session

        ``headers`` Dictionary of headers merge into session

def update_session(self, alias, headers=None, cookies=None):
        """Update Session Headers: update a HTTP Session Headers

        ``alias`` Robot Framework alias to identify the session

        ``headers`` Dictionary of headers merge into session
        """
        session = self._cache.switch(alias)
        session.headers = merge_setting(headers, session.headers)
        session.cookies = merge_cookies(session.cookies, cookies)