/**
 * hide
 */
function hide(e) {
  e.style.visibility = 'hidden';
  e.style.display = 'none';
}

/**
 * show
 */
function show(e) {
  e.style.visibility = 'visible';
  e.style.display = 'block';
}

/**
 * toggle_visibility
 */
function toggle_visibility(e) {
	if ( e.style.display == 'none' ||  e.style.display == '' ) show(e);
	else hide(e);
}