title: Swapping pair of bits in a Byte
body: <p>I have an arbitrary <strong>8-bit binary</strong> number e.g., <code>11101101</code></p>
  
  <p>I have to swap all the pair of bits like:</p>
  
  <p>Before swapping: <code>11-10-11-01</code>
  After swapping:  <code>11-01-11-10</code></p>
  
  <p>I was asked this in an interview !</p>