title: How to create a private method which takes String in any uppercase/lowercase combination and return only the first letter uppercased
body: <p>List item</p>
  
  <p>How can I create a private method called "niceLetters" which takes String in any uppercase/lowercase combination and return only the first letter uppercased and all other letters lowercased?</p>
  
  <p>e.g.</p>
  
  <p>1.) niceLetters("stEPheN") returns "Stephen"</p>
  
  <p>2.) niceLetters("HELLO") returns "Hello"</p>
  
  <p>3.)niceLEtters(null) returns null</p>
  
  <p>4.)niceLetters("") returns ""</p>