Github user robertdale commented on a diff in the pull request:
https://github.com/apache/tinkerpop/pull/621#discussion_r176237542
--- Diff:
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/strategy/optimization/ByModulatorOptimizationStrategy.java
---
@@ -0,0 +1,110 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package
org.apache.tinkerpop.gremlin.process.traversal.strategy.optimization;
+
+import org.apache.tinkerpop.gremlin.process.traversal.Step;
+import org.apache.tinkerpop.gremlin.process.traversal.Traversal;
+import org.apache.tinkerpop.gremlin.process.traversal.TraversalStrategy;
+import
org.apache.tinkerpop.gremlin.process.traversal.lambda.ElementValueTraversal;
+import
org.apache.tinkerpop.gremlin.process.traversal.lambda.IdentityTraversal;
+import
org.apache.tinkerpop.gremlin.process.traversal.lambda.TokenTraversal;
+import org.apache.tinkerpop.gremlin.process.traversal.step.ByModulating;
+import org.apache.tinkerpop.gremlin.process.traversal.step.TraversalParent;
+import org.apache.tinkerpop.gremlin.process.traversal.step.map.IdStep;
+import org.apache.tinkerpop.gremlin.process.traversal.step.map.LabelStep;
+import
org.apache.tinkerpop.gremlin.process.traversal.step.map.PropertiesStep;
+import
org.apache.tinkerpop.gremlin.process.traversal.step.sideEffect.IdentityStep;
+import
org.apache.tinkerpop.gremlin.process.traversal.strategy.AbstractTraversalStrategy;
+import org.apache.tinkerpop.gremlin.structure.PropertyType;
+import org.apache.tinkerpop.gremlin.structure.T;
+
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * This strategy looks for standard traversals in by-modulators and
replaces them with more optimized traversals
+ * (e.g. {@code TokenTraversal}) if possible.
+ * <p/>
+ *
+ * @author Daniel Kuppitz (http://gremlin.guru)
+ * @example <pre>
+ * __.path().by(id()) // is replaced by __.path().by(id)
+ * __.dedup().by(label()) // is replaced by __.dedup().by(label)
+ * __.group().by(key()) // is replaced by __.group().by(key)
+ * __.group().by(value()) // is replaced by __.group().by(value)
--- End diff --
Are key()/value() replaced? Looks like they are commented out below.
---
