Defining JQuery Function

The two below functions work as scripted except for when i add the Function next () {;} and function prev () {'} around it to define the custom function.

What am I doing wrong here?

function next() {
 
        $('#up').click(function() {
        $("#two").prev().animate({height:'80%'}, 500);
        });
     ;}
 
 
   function prev() {     
        $('#down').click(function() {
        $("#two").next().animate({height:'80%'}, 500);
        });
  ;}
 

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