title: pip3 install requests for Python3, but still not module named 'requests'
body: <p>I used <code>pip3 install requests</code> to install <code>request</code> for <code>Python3</code><br>
  This is the output:</p>
  
  <pre><code>Collecting requests
    Using cached requests-2.13.0-py2.py3-none-any.whl
  Installing collected packages: requests
  Successfully installed requests-2.13.0
  </code></pre>
  
  <p>But when I tried to import <code>requests</code> in <code>Python3</code>, an error throwed</p>
  
  <pre><code>ImportError: No module named 'requests'
  </code></pre>
  
  <p>The outputs for <code>pip3 -V</code> :  </p>
  
  <pre><code>pip 9.0.1 from /Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages (python 3.5)  
  </code></pre>
  
  <p>The outputs for <code>Python3 -V</code> : <code>Python 3.5.1</code></p>