title: Windows reports error when trying to install package using pipenv
body: <p>I installed pipenv by following the instructions <a href="https://pipenv.kennethreitz.org/en/latest/install/#installing-pipenv" rel="noreferrer">here</a>.  From the Windows command prompt I ran</p>
  
  <pre><code>pip install --user pipenv
  </code></pre>
  
  <p>which returned the message</p>
  
  <pre><code>Successfully installed pipenv-5.3.3
  </code></pre>
  
  <p>Now I want to install the <code>requests</code> package using pipenv, so I ran</p>
  
  <pre><code>pipenv install requests
  </code></pre>
  
  <p>but this returned</p>
  
  <pre><code>'pipenv' is not recognized as an internal or external command,
  operable program or batch file.
  </code></pre>
  
  <p>I have added the path</p>
  
  <pre><code>C:\Users\Robert\AppData\Roaming\Python\Python35\site-packages
  </code></pre>
  
  <p>to my Windows path environment variable, but I still receive the same error.
  How can I install the <code>requests</code> package using pipenv?</p>
  
  <hr>
  
  <p>EDIT:  As I have remnants of Python 3.5 and Python 3.6 on my system, I'm going to uninstall everything and start anew.  (I've just started learning Python and I want to keep this as simple as possible.)</p>