python: The MaD token Instance now follows subclasses

python/ql/lib/semmle/python/ApiGraphs.qll

@@ -226,6 +226,11 @@ module API {
      */
     Node getASubclass() { result = this.getASuccessor(Label::subclass()) }
 
+    /**
+     * Gets a node representing an instance of the class (or a transitive subclass of the class) represented by this node.
+     */
+    Node getAnInstance() { result = this.getASubclass*().getReturn() }
+
     /**
      * Gets a node representing the result from awaiting this node.
      */

python/ql/lib/semmle/python/frameworks/data/internal/ApiGraphModelsSpecific.qll

@@ -53,7 +53,7 @@ API::Node getExtraSuccessorFromNode(API::Node node, AccessPathTokenBase token) {
   result = node.getMember(token.getAnArgument())
   or
   token.getName() = "Instance" and
-  result = node.getReturn() // In Python `Instance` is just an alias for `ReturnValue`
+  result = node.getAnInstance()
   or
   token.getName() = "Awaited" and
   result = node.getAwaited()