title: how to solve the ValueError: is not in list
body: <p>I am having the same problem here while it is on the list actually. probably there is another mistake here is my code check it, please:</p>
  
  <pre><code>base = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"]
  c= base.index(a)
  </code></pre>
  
  <p>the a is  input and I made sure it was "o", "k"</p>
  
  <pre><code>ValueError: ['o', 'k'] is not in list
  </code></pre>
  
  <p>Also, I can't put the <code>try:</code> because this line has to be done or the whole program doesn't work</p>