doc: http://open.youku.com/docs/doc?id=84

def search_keyword_top(self, category=None, count=20, period='today'):
        """doc: http://open.youku.com/docs/doc?id=84
        """
        url = 'https://openapi.youku.com/v2/searches/keyword/top.json'
        params = {
            'client_id': self.client_id,
            'count': count,
            'period': period
        }
        if category:
            params['category'] = category
        r = requests.get(url, params=params)
        check_error(r)
        return r.json()