title: How do I handle these pandas error messages?
body: <p>Often when using pandas I get UserWarning and PerformanceWarning messages like these:</p>
  
  <pre><code>C:\Users\User\Anaconda3\lib\site-packages\pandas\core\reshape\merge.py:558: UserWarning: merging between different levels can give an unintended result (2 levels on the left, 1 on the right)
    warnings.warn(msg, UserWarning)
  
  C:\Users\User\Anaconda3\lib\site-packages\pandas\core\reshape\merge.py:558: UserWarning: merging between different levels can give an unintended result (1 levels on the left, 2 on the right)
    warnings.warn(msg, UserWarning)
  
  C:\Users\User\Anaconda3\lib\site-packages\pandas\core\generic.py:2530: PerformanceWarning: dropping on a non-lexsorted multi-index without a level parameter may impact performance.
    obj = obj._drop_axis(labels, axis, level=level, errors=errors)
  </code></pre>
  
  <p>When writing large scripts, I find difficult to know what in my code is the source of the warning.</p>
  
  <p>So how can I figure out what line of my source code generates the warning messages?</p>