Filter emoji expression using php

    / * * 
     * Filtered string expression 
     * @param $ str string Nickname 
     * @return String 
     * / 
    public  function filterEmoji ( $ STR ) {
         $ STR = the preg_replace_callback ( '/./u', function ( Array  $ match ) {
             return  strlen ( $ match [0])> =. 4 '':? $ match [0 ]; 
        } , $ STR );
         return  $ STR ; 
    }