Python: Add getAwaited to API::Node

I _really_ wanted to call this `.await()`, but that did not fit in with
the convention, or the corresponding `getPromised` in JS.

54f191cfe3/javascript/ql/src/semmle/javascript/ApiGraphs.qll (L184)

python/ql/src/semmle/python/ApiGraphs.qll

@@ -97,6 +97,11 @@ module API {
      */
     Node getASubclass() { result = getASuccessor(Label::subclass()) }
 
+    /**
+     * Gets a node representing the result from awaiting this node.
+     */
+    Node getAwaited() { result = getASuccessor(Label::await()) }
+
     /**
      * Gets a string representation of the lexicographically least among all shortest access paths
      * from the root to this node.
@@ -469,6 +474,14 @@ module API {
         exists(DataFlow::Node superclass | pred.flowsTo(superclass) |
           ref.asExpr().(ClassExpr).getABase() = superclass.asExpr()
         )
+        or
+        // awaiting
+        exists(Await await, DataFlow::Node awaitedValue |
+          lbl = Label::await() and
+          ref.asExpr() = await and
+          await.getValue() = awaitedValue.asExpr() and
+          pred.flowsTo(awaitedValue)
+        )
       )
       or
       // Built-ins, treated as members of the module `builtins`
@@ -587,4 +600,7 @@ private module Label {
 
   /** Gets the `subclass` edge label. */
   string subclass() { result = "getASubclass()" }
+
+  /** Gets the `await` edge label. */
+  string await() { result = "getAwaited()" }
 }