code: function(value) {
  			var attr = this.get('class');
  			value = utils.trim(value);
  			if (!attr) {
  				return;
  			}
  
  			var reClass = new RegExp('(^|\\s+)' + utils.escapeForRegexp(value));
  			var classVal = attr.value().replace(reClass, '');
  			if (!utils.trim(classVal)) {
  				this.remove('class');
  			} else {
  				attr.value(classVal);
  			}
  		}
docs: A special case of attribute editing: removes class value from existing
  `class` attribute
  @param {String} value