title: Python ValueError: Invalid header name b':authority
body: <p>I see the ':' is error, but I can't find  a way to solve it. </p>
  
  <pre><code>ValueError: Invalid header name b':authority'
  </code></pre>
  
  <p>It's the error:</p>
  
  <pre><code>File "tmall.py", line 23, in get_url
  response = sessions.get(url=url,headers =headers)
  
  File "E:\python\lib\site-packages\requests\sessions.py", line 501, in get
  return self.request('GET', url, **kwargs)
  
  File "E:\python\lib\site-packages\requests\sessions.py", line 488, in request
  resp = self.send(prep, **send_kwargs)
  
  File "E:\python\lib\site-packages\requests\sessions.py", line 609, in send
  r = adapter.send(request, **kwargs)
  
  File "E:\python\lib\site-packages\requests\adapters.py", line 423, in send
  timeout=timeout
  
  File "E:\python\lib\site-packages\requests\packages\urllib3\connectionpool.py", line 600, in urlopen
  chunked=chunked)
  
  File "E:\python\lib\site-packages\requests\packages\urllib3\connectionpool.py", line 356, in _make_request
  conn.request(method, url, **httplib_request_kw)
  
  File "E:\python\lib\http\client.py", line 1239, in request
  self._send_request(method, url, body, headers, encode_chunked)
  
  File "E:\python\lib\http\client.py", line 1280, in _send_request
  self.putheader(hdr, value)
  
  File "E:\python\lib\http\client.py", line 1207, in putheader
  raise ValueError('Invalid header name %r' % (header,))
  </code></pre>
  
  <hr>
  
  <p>It's the code:</p>
  
  <pre><code>import requests
  headers = {
      ':authority':'list.tmall.com',
      ':method':'GET',
      ':path':path}
  sessions = requests.session();
  response = sessions.get(url=url,headers =headers)
  </code></pre>