def test_method_is_valid(self):
		state = Tracestate()

		# empty state not allowed
		self.assertFalse(state.is_valid())

		state['foo'] = 'x' * 256
		self.assertTrue(state.is_valid())

		# exceeds 512 bytes
		state['bar'] = 'x' * 256
		self.assertFalse(state.is_valid())
		self.assertTrue(Tracestate(state.to_string()[:512]).is_valid())
		self.assertFalse(Tracestate(state.to_string()[:513]).is_valid())
        def do_POST(self):
            self.send_response(200)
            arguments = json.loads(
                str(self.rfile.read(int(self.headers['Content-Length'])),
                    'ascii'))

            traceparent = None
            tracestate = Tracestate()

            try:
                temp_traceparent = BaseTraceparent.from_string(
                    self.get_header('traceparent'))
                if temp_traceparent.version == 0:
                    if temp_traceparent._residue:
                        raise ValueError('illegal traceparent format')
                traceparent = Traceparent(0, temp_traceparent.trace_id,
                                          temp_traceparent.span_id,
                                          temp_traceparent.trace_flags)
            except ValueError:
                pass

            if traceparent is None:
                traceparent = Traceparent()
            else:
                try:
                    header = self.get_header('tracestate', commaSeparated=True)
                    if header is not None:
                        tracestate = Tracestate(header)
                except ValueError:
                    # if tracestate is malformed, reuse the traceparent instead of restart the trace
                    # traceparent = Traceparent()
                    pass

            for item in arguments:
                headers = {}
                headers['traceparent'] = str(
                    Traceparent(0, traceparent.trace_id, None,
                                traceparent.trace_flags))
                if tracestate.is_valid():
                    headers['tracestate'] = str(tracestate)
                request = Request(method='POST',
                                  url=item['url'],
                                  headers=headers,
                                  data=bytes(json.dumps(item['arguments']),
                                             'ascii'))
                with self.opener_director.open(
                        request, timeout=self.timeout) as response:
                    pass
            self.end_headers()