title: Python Error: ModuleNotFoundError: No module named '<moduleName>'
body: <p>I am trying to import several modules that I know for a fact that are installed, but I am getting the ModuleNotFoundError: No module named '' error.</p>
  
  <pre><code>$ sudo -H pip install numpy
      Requirement already satisfied: numpy in /usr/local/lib/python3.6/site-packages (1.18.1)
  $ python3
  
  Python 3.6.9 (default) 
  &gt;&gt;&gt; import numpy
  Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
  ModuleNotFoundError: No module named 'numpy'
  &gt;&gt;&gt; import PrettyTable
  Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
  ModuleNotFoundError: No module named 'PrettyTable'
  </code></pre>
  
  <p>Can you advise me on how to fix this problem?</p>