public function attr($attrKey, $attrValue = null) {
			if ( !is_null($attrValue) ) {
				if ( !is_array($this->attributes) ) {
					$this->attributes = array();
				}
				$this->attributes[$attrKey] = $attrValue;
				return $this;
			} else {
				if ( array_key_exists($attrKey, $this->attributes) ) {
					return $this->attributes[$attrKey];
				} else {
					return null;
				}
			}
			
		}