title: 'DataFrame' objects are mutable, thus they cannot be hashed || groupby().apply
body: <p>I have a trouble with pandas, Below is code:</p>
  
  <pre><code>print(right_df)
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/uLXYF.png" rel="nofollow noreferrer">enter image description here</a></p>
  
  <pre><code>print(right_top)
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/VjVGw.png" rel="nofollow noreferrer">enter image description here</a></p>
  
  <pre><code>g = right_df.groupby('exam_id').apply(right_top)
  print(g)
  </code></pre>
  
  <p>The error is "TypeError: 'DataFrame' objects are mutable, thus they cannot be hashed"
  how can i solve it??</p>