title: Comparing strings from argv
body: <p>Here is my Python2 script, <code>test.py</code>:</p>
  
  <pre><code>x = sys.argv[1]
  y = 'foo'
  print(x)
  print(y)
  print(x is y)
  </code></pre>
  
  <p>I then call my script with <code>python test.py 'foo'</code>. This prints out:</p>
  
  <pre><code>foo
  foo
  False
  </code></pre>
  
  <p>But both <code>x</code> and <code>y</code> appear to be the same value, 'foo'. So why is this equivalence test returning <code>False</code>?</p>