title: Python Error - TypeError: item 1 in _argtypes_ passes a union by value, which is unsupported
body: <p>I think this is a not a programming specific bug, but is caused by some libraries.</p>
  
  <p>I am transferring my project to a new PC, which I have freshly setup with anaconda etc. using python 3.7.6. Executing the task on the old machine works fine, here I have also used anaconda with python 3.7 (not sure if it was 3.7.6 but I could check this, i just used while creating the environment python=3.7).</p>
  
  <p>When I now try to run my program, I receive:</p>
  
  <pre><code>Exception in Tkinter callback
  Traceback (most recent call last):
  ...    
  TypeError: item 1 in _argtypes_ passes a union by value, which is unsupported.
  </code></pre>
  
  <p>The error is quite long, but it is caused by the following libraries:
  calling gym.envs which then calls some pyglet.libs</p>
  
  <p>The last line in the error is</p>
  
  <pre><code>...from pyglet.libs.x11 import xlib
    File "...7/lib/python3.7/site-packages/pyglet/libs/x11/xlib.py", line 2928, in &lt;module&gt;
      XEHeadOfExtensionList.argtypes = [XEDataObject]
  </code></pre>
  
  <p>Thank you for your help! I do not know how to solve this or even start solving it.</p>