def update_from_body(self):
        if len(self.body) > 0 or 'Content-Length' in self.headers:
            self.headers.update('Content-Length', str(len(self.body)), do_callback=False)
Called when the body of the message is modified directly. Should be used
dataset/ETHPy150Open roglew/pappy-proxy/pappyproxy/http.py/HTTPMessage.update_from_body