title: map and lambda function not doubling list elements
body: <p>I tried using the map and lambda functions in conjunction to double each integer element in a list and then print the list but it has no effect on the list and prints the original list itself.
  Following is the code snippet:</p>
  <pre><code>lis=[1,2,3,4]
  map(lambda x:x*2,lis)
  print(lis)
  </code></pre>
  <p>The output comes out to be the original list itself i.e. [1,2,3,4]</p>