title: Why does values of both variable change in Python?
body: <p>I have a small piece of code and a very big doubt.</p>
  
  <pre><code>s=['a','+','b']
  s1=s
  print s1
  del s1[1]
  print s1
  print s
  </code></pre>
  
  <p>The output is </p>
  
  <pre><code>value of s1 ['a', '+', 'b']
  value of s1 ['a', 'b']
  value of s ['a', 'b']
  </code></pre>
  
  <p>Why is the value of variable 's' changing when I am modifying s1 alone? How can I fix this?</p>
  
  <p>Thank you in advance :)</p>