title: Jupyter Extension Installation Failed: Error says 'terminado' wasn't found, but I should already have it
body: <p>I've tried to install jupyter extensions following the instruction <a href="https://jupyter-contrib-nbextensions.readthedocs.io/en/latest/install.html" rel="nofollow noreferrer">here</a>.</p>
  
  <p>The first step named 'Install the python package' in the instruction was succeeded.
  But the second one named 'Install javascript and css files' was failed.
  I executed <code>jupyter contrib nbextension install --user</code> as instructed, but an error occured.</p>
  
  <p>The error says: <code>pkg_resources.DistributionNotFound: The 'terminado&gt;=0.8.1' distribution was not found and is required by notebook</code>. (All traceback shown is as below.)
  But I confirmed that I've already installed 'terminado' v0.8.2 package, which was installed via pip.</p>
  
  <p>How can I handle this problem? Is the problem solely that jupyter command does not know where the 'terminado' is installed? Or is the problem more serious?</p>
  
  <hr>
  
  <p>All the error message is as below:</p>
  
  <pre><code>Traceback (most recent call last):
    File "/usr/local/bin/jupyter-contrib", line 5, in &lt;module&gt;
      from pkg_resources import load_entry_point
    File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/pkg_resources/__init__.py", line 3241, in &lt;module&gt;
      @_call_aside
    File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/pkg_resources/__init__.py", line 3225, in _call_aside
      f(*args, **kwargs)
    File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/pkg_resources/__init__.py", line 3254, in _initialize_master_working_set
      working_set = WorkingSet._build_master()
    File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/pkg_resources/__init__.py", line 583, in _build_master
      ws.require(__requires__)
    File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/pkg_resources/__init__.py", line 900, in require
      needed = self.resolve(parse_requirements(requirements))
    File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/pkg_resources/__init__.py", line 786, in resolve
      raise DistributionNotFound(req, requirers)
  pkg_resources.DistributionNotFound: The 'terminado&gt;=0.8.1' distribution was not found and is required by notebook
  </code></pre>
  
  <p>I'm using macOS Catalina (but same problem appeared on Mojave.</p>