code: function traverse(obj) {
        each(obj, (val, indexOrProp) => {
          // Move deeper into the object
          const next = obj[indexOrProp];
  
          // If we can go no further, then quit
          if (MongoObject.isBasicObject(next)) {
            traverse(next);
          } else if (Array.isArray(next)) {
            obj[indexOrProp] = without(next, REMOVED_MARKER);
            traverse(obj[indexOrProp]);
          }
        });
      }
docs: Traverse and pull out removed array items at this point