title: How to prevent value change in python
body: <p>For example:</p>
  
  <pre><code>&gt;&gt;&gt; state = (5,[1,2,3])
  &gt;&gt;&gt; current_state = state
  &gt;&gt;&gt; state[1].remove(3)
  &gt;&gt;&gt; state
  (5, [1, 2])
  &gt;&gt;&gt; current_state
  (5, [1, 2])
  </code></pre>
  
  <p>I changed the state but not current_state. How to keep the current_state value that equals (5,[1,2,3]) instead of removing 3 in python?</p>
  
  <p>thanks!</p>