function toggle_visibility(id) {
    var e = document.getElementById(id);
		var st = document.getElementById('signup_tut');
		var pbt = document.getElementById('paybill_tut');
		var rt = document.getElementById('refer_tut');
		var sct = document.getElementById('service_tut');

		if(e != st)
      st.style.display = 'none';
		if(e != pbt)
      pbt.style.display = 'none';
		if(e != rt)
      rt.style.display = 'none';
		if(e != sct)
      sct.style.display = 'none';

		if(e.style.display == 'block')
      e.style.display = 'none';
    else
      e.style.display = 'block';

		return true;
	}