title: How can I make some addition in Liste/Arrays (Python)
body: <p>I'm learning Liste / Matrice in Python and I would like to make some addition in Liste. Let me explain, in the exemple, in the Table "exam_liste" the second position (1 in python) I want to add +2 and refresh the table, I don't want to insert anything, I want to make an addition directly in the Liste and in my exemple it doesn't working.</p>
  
  <p>Anyone can explain me this ?</p>
  
  <pre><code> ote = 1
  
   exam_liste = [None] * 5
   print(exam_liste)
  
  
   exam_liste.insert(1,note)
   print(exam_liste)
  
   exam_liste.insert(1,exam_liste[1]+2)
   print(exam_liste)
  
   &gt;&gt;&gt; [None, None, None, None, None]
   &gt;&gt;&gt; [None, 1, None, None, None, None]
   &gt;&gt;&gt; [None, 3, 1, None, None, None, None]
  </code></pre>
  
  <p>I was waiting like : [None, <b>3</b>, None, None, None, None, None]</p>