How to use the aiozipkin.make_context function in aiozipkin

with tracer.new_trace() as span:
        span.name('client:signals')
        url = 'https://httpbin.org/get'
        # do not propagate headers
        ctx = {'span_context': span.context, 'propagate_headers': False}
        resp = await session.get(url, trace_request_ctx=ctx)
        await resp.text()
        assert resp.status == 200
        assert az.make_context(resp.request_info.headers) is None

        # by default headers added
        ctx = {'span_context': span.context}
        resp = await session.get(url, trace_request_ctx=ctx)
        await resp.text()
        assert resp.status == 200
        context = az.make_context(resp.request_info.headers)
        assert context.trace_id == span.context.trace_id

    await session.close()

    assert len(fake_transport.records) == 3
    record1 = fake_transport.records[0].asdict()
    record2 = fake_transport.records[1].asdict()
    record3 = fake_transport.records[2].asdict()
    assert record2['parentId'] == record3['id']
    assert record1['parentId'] == record3['id']
    assert record3['name'] == 'client:signals'

async def test_client_signals(tracer, fake_transport):
    trace_config = az.make_trace_config(tracer)
    session = aiohttp.ClientSession(trace_configs=[trace_config])

    with tracer.new_trace() as span:
        span.name('client:signals')
        url = 'https://httpbin.org/get'
        # do not propagate headers
        ctx = {'span_context': span.context, 'propagate_headers': False}
        resp = await session.get(url, trace_request_ctx=ctx)
        await resp.text()
        assert resp.status == 200
        assert az.make_context(resp.request_info.headers) is None

        # by default headers added
        ctx = {'span_context': span.context}
        resp = await session.get(url, trace_request_ctx=ctx)
        await resp.text()
        assert resp.status == 200
        context = az.make_context(resp.request_info.headers)
        assert context.trace_id == span.context.trace_id

    await session.close()

    assert len(fake_transport.records) == 3
    record1 = fake_transport.records[0].asdict()
    record2 = fake_transport.records[1].asdict()
    record3 = fake_transport.records[2].asdict()
    assert record2['parentId'] == record3['id']

async def consume_message(message, tracer):
    await asyncio.sleep(0.1)
    headers = message.get('headers', None)
    context = az.make_context(headers)

    with tracer.new_child(context) as span_consumer:
        span_consumer.name('consumer event')
        span_consumer.remote_endpoint('broker', ipv4='127.0.0.1', port=9011)
        span_consumer.kind(az.CONSUMER)

    with tracer.new_child(span_consumer.context) as span_worker:
        span_worker.name('process event')
        await asyncio.sleep(0.1)