title: url lib error python
body: <p>I am trying to download a dataset file via a URL,but the problem is I am receiving this message.</p>
  
  <pre><code> File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/urllib/request.py", line 1320, in do_open
      raise URLError(err)
  urllib.error.URLError: &lt;urlopen error [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:749)&gt;
  
  Process finished with exit code 1
  </code></pre>
  
  <p>I am not sure what is it that I am doing wrong, since I am following a tutorial online. 
  Here is the file I am running, everything is okay but the problem is when it comes the time to run the url for downloading.</p>
  
  <pre><code>print("download will complete at about 423 MB")
  
  
  import sys
  
  if sys.version_info[0] &gt;= 3:
      from urllib.request import urlretrieve
  else:
      from urllib import urlretrieve
  
  url = "https://www.cs.cmu.edu/~./enron/enron_mail_20150507.tgz"
  urlretrieve(url, filename="../enron_mail_20150507.tgz")
  print("download complete!")
  
  
  print()
  print("unzipping Enron dataset (this may take a while)")
  import tarfile
  import os
  os.chdir("..")
  tfile = tarfile.open("enron_mail_20150507.tgz", "r:gz")
  tfile.extractall(".")
  </code></pre>