title: How to edit CPython's Lib/importlib/_bootstrap.py?
body: <p>I would like to play with CPython's Lib/importlib/_bootstrap.py file, but my edits in my current CPython installation on MacOS (installed with the Homebrew package manager) have no effect when I import a module.</p>
  
  <p>For instance if I add the <code>print("hello", file=sys.stderr)</code> statement at the beginning of the body of the <code>_init_module_attrs</code> function:</p>
  
  <pre><code>$ vi /usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/importlib/_bootstrap.py
  </code></pre>
  
  <p>and then import a module:</p>
  
  <pre><code>$ python3 -c "import pathlib"
  </code></pre>
  
  <p>nothing is printed.</p>