code: function(key) {
  			this.writeDebug('_existingRadioFilters',arguments);
  			$('#' + this.settings.taxonomyFilters[key] + ' input[type=radio]').each(function () {
  				if ($(this).prop('checked')) {
  					var filterVal = $(this).val();
  
  					// Only add the taxonomy id if it doesn't already exist
  					if (typeof filterVal !== 'undefined' && filterVal !== '' && filters[key].indexOf(filterVal) === -1) {
  						filters[key] = [filterVal];
  					}
  				}
  			});
  		}
docs: Find the existing selected value for each radio button filter - private
  
  @param key {string} object key