title: Swapping every second character in a string in Python
body: <p>I have the following problem: I would like to write a function in Python which, <strong>given a string</strong>, returns a <strong>string</strong> where <strong>every group of two characters is swapped</strong>.</p>
  
  <p>For example given "ABCDEF" it returns "BADCFE". </p>
  
  <p>The length of the string would be guaranteed to be an even number.</p>
  
  <p>Can you help me how to do it in Python?</p>