To make a GET request to Falkonry API server and return stream
        :param url: string

def downstream(self, url, format):
        """
        To make a GET request to Falkonry API server and return stream
        :param url: string
        """
        headers={'Authorization': 'Bearer '+self.token, 'x-falkonry-source':self.sourceHeader}
        if format is not None:
            headers['accept'] = format
        response = requests.get(self.host + url, stream=True, headers=headers, verify=False)
        if response.status_code == 200 or response.status_code == 202:
            return response
        elif response.status_code == 401:
            raise Exception(json.dumps({'message':'Unauthorized Access'}))
        else:
            raise Exception(json.dumps({'message':str(response.text)}))