tests/basics: Add tests for variable annotations.

tests/basics/annotate_var.py

@@ -0,0 +1,25 @@
+# test PEP 526, varible annotations
+
+x: int
+print("x" in globals())
+
+x: int = 1
+print(x)
+
+t: tuple = 1, 2
+print(t)
+
+# a pure annotation in a function makes that variable local
+def f():
+    x: int
+    try:
+        print(x)
+    except NameError:
+        print("NameError")
+f()
+
+# here, "x" should remain a global
+def f():
+    x.y: int
+    print(x)
+f()