title: Find index of a tuple in a list of tuples
body: <p>I have a list of tuples and I want to find the index of a tuple if the tuple contains a variable. Here is a simple code of what I have so far:</p>
  <pre><code>items = [('show_scllo1', '100'), ('show_scllo2', '200')]
  s = 'show_scllo1'
  indx = items.index([tupl for tupl in items if tupl[0] == s])
  print(indx)
  </code></pre>
  <p>However I am getting the error:</p>
  <pre><code>indx = items.index([tupl for tupl in items if tupl[0] == s])
  ValueError: list.index(x): x not in list
  </code></pre>
  <p>What I am doing wrong?</p>