title: Why [:][:1] don't work for list of tuples? How can I get iterable for a some index in all tuples in list?
body: <p>I know how to match tuples in list. It's</p>
  
  <pre><code>a=[('a','b','c'),('d','e','f'),('g','h','i')]
  if ('a','b','c') in a:
      print('it is')
  </code></pre>
  
  <p>But I need a partial match. ('a', 'b', 'j') should match ('a', 'b', 'c').
  Maybe b[:2] for b in a?</p>