title: Get emoticon unicode from char UTF-16
body: <p>I need to intercept an emoticon entry and change for my own emoticon. 
  When I intercept an emoticon, for example, the FACE WITH MEDICAL MASK (\U+1F604), I get an UTF-16 char (0xD83D 0xDE04), Is it possible to convert this char value to the unicode value?</p>
  
  <p>I need to convert 0xD83D 0xDE04 to \u1f604.</p>
  
  <p>Thanks,</p>