title: how to remove the "User-Agent" header when send request in python
body: <p>I'm using <a href="https://docs.python-requests.org/en/latest/" rel="noreferrer">python requests</a> library, I need send a request without a user-agent header.
  I found <a href="https://stackoverflow.com/questions/32954366/python3-urllib2-need-to-remove-the-user-agent-header-completely">this question</a>, but it's for Urllib2.</p>
  <p>I'm trying to simulate an Android app which does this when calling a private API.</p>
  <p>I try to set <code>User-Agent</code> to <code>None</code> as in the following code, but it doesn't work. It still sends <code>User-Agent: python-requests/2.27.1</code>.</p>
  <p>Is there any way?</p>
  <pre><code>headers = requests.utils.default_headers()
  headers['User-Agent'] = None
  requests.post(url, *args, headers=headers, **kwargs)
  </code></pre>