function left_menu() {
	var els = getElementsByClass('left_div');
	for(i=0; i < els.length; i++) {
		if (spanEl = els[i].getElementsByTagName('SPAN')[0]) {		
			spanEl.onclick = function() {
				if(divEl = this.parentNode.getElementsByTagName('DIV')[0]) {				
					if(this.className == 'left_arrow_bottom') {
						this.className = 'left_arrow_top';
						$(divEl).slideDown();			
					}
					else { 
						$(divEl).slideUp();
						this.className = 'left_arrow_bottom'; 
					}	
				}					
			};
		}
	}
}

bs.onReady(function() {
	left_menu();
});