code: function(c, i, array) {
        if (c === undefined || c === null) return;
        // c is the component, type is dimension|attribute,
        // level is dataset|series|observation, i is index,
        // array is the component array
        failed += !iterator.call(context, c, type, level, i, array);
      }
docs: Applies the iterator function and collects boolean results