add some Python 2 modules

python2/gc.py

@@ -0,0 +1,30 @@
+# This is an autogenerated file. It serves as a starting point
+# for a more percise manual annotation of this module.
+# Feel free to edit the source below, but remove this header when you do.
+
+def set_debug(a: int) -> NoneType: pass
+
+def get_threshold() -> tuple: pass
+
+def collect(*args, **kwargs) -> int:
+    raise ValueError()
+
+def is_tracked(*args, **kwargs) -> bool: pass
+
+def get_referents(*args, **kwargs) -> list: pass
+
+def isenabled() -> bool: pass
+
+def set_threshold(a: int, *args, **kwargs) -> NoneType: pass
+
+def get_debug() -> int: pass
+
+def disable() -> NoneType: pass
+
+def get_count() -> tuple: pass
+
+def enable() -> NoneType: pass
+
+def get_objects() -> list: pass
+
+def get_referrers(*args, **kwargs) -> list: pass