Add some tests for python3.

test/normalizer_issue_files/python3.py

@@ -0,0 +1,18 @@
+#!/usr/bin/env python3
+from typing import ClassVar, List
+
+
+# Annotated function (Issue #29)
+def foo(x: int) -> int:
+    return x + 1
+
+
+# Annotated variables #575
+CONST: int = 42
+
+
+class Class:
+    cls_var: ClassVar[str]
+
+    def m(self):
+        xs: List[int] = []