title: Remove from one list impact it's copy [python 2.7]
body: <p>I created a copy of a list.
  When an item was removed from one copy - it was removed from the original as well.</p>
  <pre><code>a = ['alpha', 'beta', 'gamma', 'delta']
  b = a
  
  b.remove('alpha')
  
  print 'A list is', a
  print 'B list is', b
  </code></pre>
  <p>How should I create an independent copy of the list, that will not impact the original?</p>
  <h2>Late addition</h2>
  <p>To understand the reason for this mistake - one should refer to the difference between Shallow Copy and Deep Copy <a href="https://docs.python.org/2/library/copy.html" rel="nofollow noreferrer">Python documentation - 8.17. copy</a></p>
  <blockquote>
  <p>The difference between shallow and deep copying is only relevant for compound objects (objects that contain other objects, like lists or class instances):</p>
  <ul>
  <li>A shallow copy constructs a new compound object and then (to the extent possible) inserts references into it to the objects found in the original.</li>
  <li>A deep copy constructs a new compound object and then, recursively, inserts copies into it of the objects found in the original.</li>
  </ul>
  </blockquote>