Added implicit-return to Python functions

This is important when working with clusters, as it differentiates between the case
where the cluster has a return and when it does not.

Author: tmr232

src/control-flow/cfg-python.ts

@@ -35,13 +35,15 @@ export class CFGBuilder {
     const bodyNode = functionNode.childForFieldName("body");
     if (bodyNode) {
       const blockHandler = new BlockHandler();
-      const { entry } = blockHandler.update(
+      const { entry, exit } = blockHandler.update(
         this.processStatements(bodyNode.namedChildren),
       );
 
       const startNode = this.addNode("START", "START");
+      const endNode = this.addNode("RETURN", "implicit return");
       // `entry` will be non-null for any valid code
       if (entry) this.addEdge(startNode, entry);
+      if (exit) this.addEdge(exit, endNode)
       this.entry = startNode;
     }
     return { graph: this.graph, entry: this.entry };

src/test/commentTestSamples/sample.py

@@ -163,5 +163,15 @@ def try_finally():
         if x:
             return
         pass
+    finally:
+        pass
+
+# exits: 5,
+# render: true
+def try_finally():
+    try:
+        with x:
+            return
+        pass
     finally:
         pass