@Test
    public void shouldSupplyNewMeanNumberOnEachInvocation() {
        final MeanGlobalStep.MeanNumber l1 = MeanNumberSupplier.instance().get();
        final MeanGlobalStep.MeanNumber l2 = MeanNumberSupplier.instance().get();
        final MeanGlobalStep.MeanNumber l3 = MeanNumberSupplier.instance().get();

        assertNotSame(l1, l2);
        assertNotSame(l1, l3);
        assertNotSame(l2, l3);
    }
@author Stephen Mallette (http://stephen.genoprime.com)
gremlin-core/src/test/java/org/apache/tinkerpop/gremlin/util/function/MeanNumberSupplierTest.java