public static <T> org.hamcrest.Matcher<T> in(final Collection<T> collection) {
        return new IsInMatcher(collection);
    }
TinkerPop version of Hamcrest's {code in} that can use our custom assertions for {@link Path}.
gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/features/StepDefinition.java