title: Where is the source code for notebook/static/components/?
body: <p>I have installed jupyter notebook.  In the installed package there is a directory:</p>
  <p><code>~/.local/lib/python3.8/site-packages/notebook/static/components/</code></p>
  <p>But, when I look at <a href="https://github.com/jupyter/notebook/tree/master/notebook/static/" rel="nofollow noreferrer">https://github.com/jupyter/notebook/tree/master/notebook/static/</a> then I see no <strong><code>components</code></strong> diretory.  Maybe I'm looking in the wrong place for the source code?  Maybe <a href="https://github.com/jupyter/notebook/" rel="nofollow noreferrer">https://github.com/jupyter/notebook/</a> is not the correct source code?</p>
  <p>All of the other directories in <a href="https://github.com/jupyter/notebook/tree/master/notebook/static/" rel="nofollow noreferrer">https://github.com/jupyter/notebook/tree/master/notebook/static/</a> <em><strong>match</strong></em> one for one with those in my installation <code>~/.local/lib/python3.8/site-packages/notebook/static</code> ... only the <code>components</code> directory <strong>is</strong> in my installation but is <strong>not in</strong> <a href="https://github.com/jupyter/notebook/tree/master/notebook/static/" rel="nofollow noreferrer">https://github.com/jupyter/notebook/tree/master/notebook/static/</a></p>
  <p>Can anyone explain the discrepancy?</p>
  <hr />
  <p>P.S.  I just now noticed it appears that the <code>components</code> directory is installed separately: <a href="https://github.com/jupyter/notebook/blob/master/setupbase.py#L92-L168" rel="nofollow noreferrer">https://github.com/jupyter/notebook/blob/master/setupbase.py#L92-L168</a>  ... However (not being an expert in setup.py) it's still not clear to me <em>where all the files under the components directory are coming from</em>.</p>
  <hr />
  <p>P.P.S.  I'm beginning to see what is going on here.  In my jupyter notebook installation, all of the directories under <code>static/components</code> appear to be coming from other repositories.  For example, there is a directory called <code>static/components/codemirror</code> containing other directories and files all of which appear to be coming from here: <a href="https://github.com/codemirror/CodeMirror" rel="nofollow noreferrer">https://github.com/codemirror/CodeMirror</a></p>
  <p><em>Can anyone give me a brief summary of this feature of setuptools that apparently allows one to install files from multiple repositories,  Please also, if you can, indicate when and why one would want to use this feature (as opposed to simply requiring installation of those other packages) and also point me in the directory of documentation about it?</em></p>