title: In Python a tuple is immutable object but allows mutation of a contained list?
body: <p>In Python:</p>
  
  <pre><code>&gt;&gt;&gt; tup = (1,"a",[1,2,3])
  &gt;&gt;&gt; tup
  (1, 'a', [1, 2, 3])
  &gt;&gt;&gt; tup[2][1] = "a"
  &gt;&gt;&gt; tup
  (1, 'a', [1, 'a', 3])
  </code></pre>
  
  <p>From the above I could modify the list contents which is part of the tuple. Since tuple is immutable how is this possible?
  Did I understood the immutable part in a wrong way?</p>