python: update comments

Author: yoff

python/ql/test/experimental/dataflow/variable-capture/global.py

@@ -1,4 +1,4 @@
-# Here we test writing to a captured variable via the `nonlocal` keyword (see `out`).
+# Here we test writing to a captured global variable via the `global` keyword (see `out`).
 # We also test reading one captured variable and writing the value to another (see `through`).
 
 # All functions starting with "test_" should run and execute `print("OK")` exactly once.

python/ql/test/library-tests/ApiGraphs/py3/test_captured_inheritance.py

@@ -13,7 +13,11 @@ class Baz(A): pass
 
     def other_func():
         print(Foo)  #$ use=moduleImport("foo").getMember("A").getASubclass() use=moduleImport("foo").getMember("B").getASubclass()
-        print(Bar)  #$ use=moduleImport("foo").getMember("B").getASubclass() MISSING: use=moduleImport("foo").getMember("A").getASubclass()  The MISSING here is documenting correct behaviour
+        # On the next line, we wish to express that it is not possible for `Bar` to be a subclass of `A`.
+        # However, we have no "true negative" annotation, so we use the MISSING annotation instead.
+        # (Normally, "true negative" is not needed as all applicable annotations must be present,
+        # but for type tracking tests, this would be excessive.)
+        print(Bar)  #$ use=moduleImport("foo").getMember("B").getASubclass() MISSING: use=moduleImport("foo").getMember("A").getASubclass()
         print(Baz)  #$ use=moduleImport("foo").getMember("B").getASubclass() SPURIOUS: use=moduleImport("foo").getMember("A").getASubclass()
 
     class Baz(B): pass