diff --git a/core/src/main/java/io/parsingdata/metal/expression/Expression.java b/core/src/main/java/io/parsingdata/metal/expression/Expression.java
index 2421ecd1..f80b3d7d 100644
--- a/core/src/main/java/io/parsingdata/metal/expression/Expression.java
+++ b/core/src/main/java/io/parsingdata/metal/expression/Expression.java
@@ -38,4 +38,5 @@ public interface Expression {
 
     ImmutableList<Boolean> eval(ParseGraph graph, Encoding encoding);
 
+    // TODO: should the reducing operation be present here? See Util#allTrue
 }
diff --git a/core/src/main/java/io/parsingdata/metal/expression/comparison/ComparisonExpression.java b/core/src/main/java/io/parsingdata/metal/expression/comparison/ComparisonExpression.java
index da1dff76..8375f5d8 100644
--- a/core/src/main/java/io/parsingdata/metal/expression/comparison/ComparisonExpression.java
+++ b/core/src/main/java/io/parsingdata/metal/expression/comparison/ComparisonExpression.java
@@ -16,11 +16,12 @@
 
 package io.parsingdata.metal.expression.comparison;
 
+import static java.util.function.Function.identity;
+
 import static io.parsingdata.metal.SafeTrampoline.complete;
 import static io.parsingdata.metal.SafeTrampoline.intermediate;
 import static io.parsingdata.metal.Util.checkNotNull;
 import static io.parsingdata.metal.data.transformation.Reversal.reverse;
-import static java.util.function.Function.identity;
 
 import java.util.Objects;
 import java.util.Optional;
diff --git a/core/src/main/java/io/parsingdata/metal/token/While.java b/core/src/main/java/io/parsingdata/metal/token/While.java
index a19624f2..89c4b91f 100644
--- a/core/src/main/java/io/parsingdata/metal/token/While.java
+++ b/core/src/main/java/io/parsingdata/metal/token/While.java
@@ -16,6 +16,7 @@
 
 package io.parsingdata.metal.token;
 
+import static io.parsingdata.metal.Shorthand.expTrue;
 import static io.parsingdata.metal.Trampoline.complete;
 import static io.parsingdata.metal.Trampoline.intermediate;
 import static io.parsingdata.metal.Util.allTrue;
@@ -26,8 +27,6 @@
 import java.util.Objects;
 import java.util.Optional;
 
-import static io.parsingdata.metal.Shorthand.expTrue;
-
 import io.parsingdata.metal.Trampoline;
 import io.parsingdata.metal.Util;
 import io.parsingdata.metal.data.Environment;
diff --git a/core/src/test/java/io/parsingdata/metal/CompoundExpressionTest.java b/core/src/test/java/io/parsingdata/metal/CompoundExpressionTest.java
index 0cab23e6..2a04d36d 100644
--- a/core/src/test/java/io/parsingdata/metal/CompoundExpressionTest.java
+++ b/core/src/test/java/io/parsingdata/metal/CompoundExpressionTest.java
@@ -1,3 +1,19 @@
+/*
+ * Copyright 2013-2016 Netherlands Forensic Institute
+ *
+ * Licensed 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 io.parsingdata.metal;
 
 import static io.parsingdata.metal.Util.allTrue;
@@ -64,8 +80,8 @@ public void evalGtEqNum() throws IOException {
         assertFalse(allTrue(gtEqNum(ref("value"), rev(ref("other"))).eval(graph, enc())));
     }
 
-    private static Expression imp(final Expression l, final Expression r) {
-        return or(not(l), r);
+    private static Expression imp(final Expression left, final Expression right) {
+        return or(not(left), right);
     }
 
     private static Expression gtEqNum(final ValueExpression value, final ValueExpression predicate) {