title: 'set' object has no attribute 'setdefault'. Error in scraping data using using Requests
body: <p>I am trying to hit a website using python Requests, but it's giving me error. </p>
  
  <pre><code>import requests 
  headers = {'User-Agent': 'Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.67 Safari/537.36'}
  URL = ""
  PROXY = {'https://surfproxy.de.db.com:8080' }
  response = requests.get(URL , proxies = PROXY, headers: headers)
  </code></pre>
  
  <p>The error logs:</p>
  
  <blockquote>
    <p>File "", line 1, in 
        runfile('C:/Users/vermanjb/JiraScrapping.py', wdir='C:/Users/vermanjb')</p>
    
    <p>File "C:\Program
    Files\Anaconda3\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.py",
    line 699, in runfile
        execfile(filename, namespace)</p>
    
    <p>File "C:\Program
    Files\Anaconda3\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.py",
    line 88, in execfile
        exec(compile(open(filename, 'rb').read(), filename, 'exec'), namespace)</p>
    
    <p>File "C:/Users/vermanjb/JiraScrapping.py", line 12, in 
        response = requests.get(URL , proxies = PROXY)</p>
    
    <p>File "C:\Program Files\Anaconda3\lib\site-packages\requests\api.py",
    line 67, in get
        return request('get', url, params=params, **kwargs)</p>
    
    <p>File "C:\Program Files\Anaconda3\lib\site-packages\requests\api.py",
    line 53, in request
        return session.request(method=method, url=url, **kwargs)</p>
    
    <p>File "C:\Program
    Files\Anaconda3\lib\site-packages\requests\sessions.py", line 459, in
    request
        prep.url, proxies, stream, verify, cert</p>
    
    <p>File "C:\Program
    Files\Anaconda3\lib\site-packages\requests\sessions.py", line 619, in
    merge_environment_settings
        proxies.setdefault(k, v)</p>
    
    <p>AttributeError: 'set' object has no attribute 'setdefault'</p>
  </blockquote>