title: why can't I install flake8 by pip?
body: <p>I did like this</p>
  
  <pre><code>pip install flake8
  </code></pre>
  
  <p>then, terminal says that it has already installed and it is in 
  <code>.pyenv/versions/anaconda3-2.1.0/lib/python3.4/site-packages.</code> But,I did like this</p>
  
  <pre><code>which flake8
  </code></pre>
  
  <p>then, terminal says nothing. Why? I couldn't install that ?</p>