title: Single quoted string vs. double quoted string
body: <p>Why do we need an escape character for single quoted string, but not for a double quoted string?</p>
  
  <pre><code>a = 'hello how\'s it going'
  a1 = 'hello how's it going'
  b =  "hello how's it going"
  
  assert(a==b) # Passes
  
  assert(a1==b) # Errors
  </code></pre>
  
  <p>The error message:</p>
  
  <pre>
   File "string.py", line 1
      a = 'hello how's it going'
                    ^
  SyntaxError: invalid syntax
  </pre>