Github user nickwallen commented on a diff in the pull request:
https://github.com/apache/metron/pull/884#discussion_r159498766
--- Diff:
metron-stellar/stellar-common/src/main/java/org/apache/metron/stellar/common/shell/specials/DocCommand.java
---
@@ -0,0 +1,105 @@
+/*
+ * 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.metron.stellar.common.shell.specials;
+
+import org.apache.commons.lang3.StringUtils;
+import org.apache.metron.stellar.common.shell.StellarShellExecutor;
+import org.apache.metron.stellar.common.shell.StellarResult;
+import org.apache.metron.stellar.dsl.StellarFunctionInfo;
+
+import java.util.Optional;
+import java.util.Spliterator;
+import java.util.function.Function;
+import java.util.stream.StreamSupport;
+
+import static org.apache.metron.stellar.common.shell.StellarResult.error;
+import static org.apache.metron.stellar.common.shell.StellarResult.success;
+
+/**
+ * A special command that allows a user to request doc string
+ * about a Stellar function.
+ *
+ * For example `?TO_STRING` will output the docs for the function
`TO_STRING`
+ */
+public class DocCommand implements SpecialCommand {
--- End diff --
Doc strings are not part of the core language.
---
