Python: fix some consistencies

There is still the case of comprehensions,
where TFunction is not defined and so
getEnclosingCallable does not exist.

Author: yoff

python/ql/lib/semmle/python/dataflow/new/internal/DataFlowPublic.qll

@@ -118,7 +118,7 @@ newtype TNode =
   } or
   /** A synthetic node representing a captured variable. */
   TCaptureNode(VariableCapture::Flow::SynthesizedCaptureNode cn) or
-  /** TODO: extende to also cover lambdas */
+  /** A synthetic node representing the heap of a function. Used for variable capture. */
   TLambdaSelfReferenceNode(Function f) {
     f = any(VariableCapture::CapturedVariable v).getACapturingScope()
   }
@@ -489,7 +489,11 @@ class CaptureNode extends Node, TCaptureNode {
 
   VariableCapture::Flow::SynthesizedCaptureNode getSynthesizedCaptureNode() { result = cn }
 
-  override DataFlowCallable getEnclosingCallable() { result = TFunction(cn.getEnclosingCallable()) }
+  override DataFlowCallable getEnclosingCallable() {
+    result = TFunction(cn.getEnclosingCallable())
+    or
+    result = TModule(cn.getEnclosingCallable())
+  }
 
   override Location getLocation() { result = cn.getLocation() }