@Override
    default void close() {
        // do nothing by default
    }
Wraps an existing {@code Iterator} in a {@code CloseableIterator}. If the {@code Iterator} is already of that
type then it will simply be returned as-is.
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/structure/util/CloseableIterator.java