title: How to solve ImportError: dlopen(): Symbol not found:.... Expected in: flat namespace
body: <p>Can anyone help me solve this issue?</p>
  
  <pre><code>ImportError: dlopen(/Users/......./venv/lib/python3.6/site-packages/recordclass/mutabletuple.cpython-36m-darwin.so, 2): Symbol not found: __PyEval_GetBuiltinId
    Referenced from: /Users/......./venv/lib/python3.6/site-packages/recordclass/mutabletuple.cpython-36m-darwin.so
    Expected in: flat namespace
   in /Users/......../venv/lib/python3.6/site-packages/recordclass/mutabletuple.cpython-36m-darwin.so
  </code></pre>
  
  <p>I'm using a Mac if that's of any relevance</p>